5-methylene-1,3-dioxolan-4-one derivatives, process for their production, polymers of the derivatives, resist compositions, and pattern formation process

ABSTRACT

A 5-methylene-1,3-dioxolan-4-one derivative and a monomer and copolymer thereof and a resist composition containing the polymer or copolymer where the 5-methylene-1,3 -dioxolan-4-one derivative is of formula (1): 
                         
wherein R 1  represents a bridged cyclic hydrocarbon group containing 4 to 16 carbon atoms, or a linear or branched alkyl group containing 1 to 6 carbon atoms which has a bridged cyclic hydrocarbon group containing 4 to 16 carbon atoms as a substituent; R 2  represents a hydrogen atom, or a linear or branched alkyl group containing 1 to 6 carbon atoms; or R 1  and R 2  represent a bridged cyclic hydrocarbon group containing 4 to 16 carbon atoms together with the carbon atom to which they are bound, provided that the alkyl group and the bridged cyclic hydrocarbon group may have at least one substituent selected from a group consisting of a linear or branched alkyl group containing 1 to 6 carbon atoms which may be optionally substituted, a hydroxy group, a carboxy group, an acyl group containing 2 to 6 carbon atoms, an alkoxy group containing 1 to 6 carbon atoms, and a carboxy group esterified with an alcohol containing 1 to 6 carbon atoms.

TECHNICAL FIELD

The present invention relates to a 5-methylene-1,3-dioxolan-4-onederivative having, at position 2, a bridged cyclic hydrocarbon group oralkyl group substituted with a bridged cyclic hydrocarbon group, whichis useful as a raw material monomer for a component resin of a coatingmaterial, an adhesive, an agglutinant, a resin for ink, a resist or thelike, and a production method thereof. Moreover, the present inventionrelates to a polymer obtained by polymerizing the5-methylene-1,3-dioxolan-4-one derivative, which is useful for a resistor the like. In particular, it relates to a polymer for a resist, whichis suitable for microfabrication using an excimer laser or electronbeam, a resist composition comprising the polymer, and a patternformation method.

BACKGROUND ART

Various compounds and production methods thereof have previously beenknown regarding a 5-methylene-1,3-dioxolan-4-one derivative representedby the following general formula (A):

wherein each of R²³ and R²⁴ represents a hydrogen atom, an alkyl group,an aryl group which may be optionally substituted, or a cyclohexylgroup; or R²³ and R²⁴ may form a phenyl group or a cyclic structure of(CH₂)_(m) together with the carbon atom to which they are bound,

wherein the substituent on the aryl group is a linear or branched alkylgroup containing 1 to 12 carbon atoms or a halogen atom, and m is aninteger of 2 or greater.

For example, J. Organic Chemical, 57(12), 3380 (1992) and TetrahedronLett., 30(52), 7305 (1989) describe a method of producing the5-methylene-1,3-dioxolan-4-one derivative via a5-(phenylthio)methyl-1,3-dioxolan-4-one derivative obtained by reactinga compound wherein, in the above formula (A), R²³ represents a hydrogenatom and R²⁴ represents a t-butyl group or a cyclohexyl group, andβ-(thiophenoxy)methyllactate, with a ketone or an aldehyde. However, themethod of producing the above derivative of interest via the5-(phenylthio)methyl-1,3-dioxolan-4-one derivative has very complicatedsteps in which the 5-(phenylthio)methyl-1,3-dioxolan-4-one derivative isoxidized at −78° C. using 3-chloroperbenzoic acid followed by atreatment with triethyl phosphate at 210° C.

Japanese Patent Laid-Open No. 7-70106 discloses a compound wherein, inthe above formula (A), R²³ represents a hydrogen atom and R²⁴ representsa substituted or unsubstituted alkyl group or a substituted orunsubstituted aryl group (more specifically,2-tert-butyl-5-methylene-1,3-dioxolan-4-one). In addition, the abovepublished application also discloses a method of producing the compoundby reacting a 5-halogeno-5-methyl-1,3-dioxolane-4-one derivative such as2-tert-butyl-5-bromo-5-methyl-1,3-dioxolan-4-one with a tertiary aminesuch as trioctylamine or tributylamine in a solvent such as carbontetrachloride or cyclohexane under reflux, and carrying out adehydrohalogenation reaction.

Japanese Patent Laid-Open No. 10-316609 discloses a compound wherein, inthe above formula (A), each of R²³ and R²⁴ represents an alkyl group(more specifically,2-tert-butyl-2-methyl-5-methylene-1,3-dioxolan-4-one, etc.). Moreover,the above published application also discloses a method of producing thecompound, which comprises: reacting2,2-disubstituted-5-methyl-1,3-dioxolan-4-one such as2-tert-butyl-2,5-dimethyl-1,3-dioxolan-4-one, etc., which is synthesizedfrom ketones and lactic acid, with a halogenating agent such asN-bromosuccinimide in a solvent such as cyclohexane under reflux, so asto obtain 2,2-disubstituted-5-halogeno-5-methyl-1,3-dioxolan-4-one;reacting the obtained compound with a tertiary amine such astrioctylamine or triethylamine in a solvent such as cyclohexane underreflux and carrying out a dehydrohalogenation reaction.

Furthermore, USSR Patent No. 606,313 describes a compound wherein, inthe above formula (A), each of R²³ and R²⁴ represents a hydrogen atom oran aryl group, or R²³ and R²⁴ form a cyclic structure (CH₂)_(m) (whereinm represents an integer of 2 or greater). Polym. Prepr. (Am. ChemicalSociety, Div. Polym. Chemical), 28(1), 154 (1987) describes a compoundwherein, in the above formula (A), each of R²³ and R²⁴ represents amethyl group. Japanese Patent Laid-Open No. 3-37214 discloses a compoundwherein, in the above formula (A), each of R²³ and R²⁴ represents ahydrogen atom, a phenyl group having an alkyl group containing 1 to 12carbon atoms or a halogen atom as a substituent, or an alkyl groupcontaining 1 to 12 carbon atoms. Still further, all of the above USSRPatent No. 606,313, Polym. Prepr. (Am. Chemical Society, Div. Polym.Chemical), 28(1), 154 (1987), and Japanese Patent Laid-Open No. 3-37214describe a production method comprising reacting β-halolactic acid witha ketone or an aldehyde to synthesize a 5-halomethyl-1,3-dioxolan-4-onederivative, and subjecting it to a dehydrohalogenation reaction with abase such as amine.

However, a 5-methylene-1,3-dioxolan-4-one derivative having a bridgedcyclic hydrocarbon structure as a substituent and a production methodthereof have not been reported so far.

Moreover, several polymers obtained by polymerizing monomers having a5-methylene-1,3-dioxolan-4-one structure have been known as awater-soluble polymer, a biodegradable polymer, or the like. Forexample, T. Endo et al., Macromol. Chem. Phys., 202, 1602 (2001)describes a copolymer of 2,2-dimethyl-5-methylene-1,3-dioxolan-4-one andmethyl methacrylate. Chin. J. Polym. Sci., 10, 350 (1992) describes apolymer of 2-phenyl-5-methylene-1,3-dioxolan-4-one.

However, a polymer of 5-methylene-1,3-dioxolan-4-one derivatives havinga substituent with a bridged cyclic hydrocarbon structure has not beenreported so far.

By the way, recently, in the field of microfabrication for production ofa semiconductor device or a liquid crystal device, a miniaturizationtechnique has been quickly progressed to realize high-density andhigh-accumulation of a device against the backdrop of the advancement ina lithographic technique. As such a microfabrication technique, theconversion of an exposure source into the light source with a shorterwavelength has generally been used. Specifically, the exposure sourcehas been changed from the previous ultraviolet ray, as represented by ag-ray (wavelength: 438 nm) or an i-ray (wavelength: 365 nm) to a farultraviolet ray.

Presently, a KrF excimer laser (wavelength: 248 nm) lithographictechnique has been introduced in the market, and an ArF excimer laser(wavelength: 193 nm) lithographic technique, which is directed towardsthe conversion of an exposure source into the source with a furthershorter wavelength, is being introduced in the market. Moreover, an F₂excimer laser (wavelength: 157 nm) lithographic technique is studied asa technique for the next generation. Furthermore, an electron beamlithographic technique, which is a somewhat different type from theabove techniques, is also intensively studied.

As a resist with high sensitivity for such a light source with a shortwavelength or an electron beam, a “chemically amplified resist” has beenproposed by International Business Machine (IBM) Corporation, and atpresent, the improvement and development of this chemically amplifiedresist have been advanced vigorously.

By the way, in the conversion of the light source into the one with ashorter wavelength, a resin used for the resist is also forced to changeits structure. For example, in the KrF excimer laser lithography,polyhydroxystyrene having high transparency to the light with awavelength of 248 nm, a compound wherein the hydroxyl group thereofprotected with an acid-dissociating solubility-inhibiting group, or thelike are used. However, in the ArF excimer laser lithography, often theabove resins cannot be used because they do not always have sufficienttransparency to the light with a wavelength of 193 nm.

Accordingly, an acrylic resin or a cycloolefin resin that aretransparent to the light with a wavelength of 193 nm attract attentionas a resist resin used in the ArF excimer laser lithography. Such anacrylic resin is disclosed in published applications such as JapanesePatent Laid-Open Nos. 4-39665, 10-207069 and 9-090637, and such acycloolefin resin is disclosed in published applications such asJapanese Patent Laid-Open No. 10-153864.

In particular, a copolymer of 2-methyl-2-adamantyl methacrylate drawsthe attention as a resist resin used in the ArF excimer laserlithography. This copolymer is described in S. Takechi et al., Journalof Photopolymer Science and Technology, Vol. 9, No. 3, 475-487 (1996)and Japanese Patent Laid-Open No. 9-73173. With regard to thiscopolymer, it has been reported that 2-methyl-2-adamantyl is cleaved bythe action of an acid so that it acts as a positive type, and that thecopolymer provides high dry etching resistance, high sensitivity andhigh resolution. However, such a copolymer having an alicyclic skeletongenerally tends to have high hydrophobicity, and it does not havesufficient wettability to a developing solution in some cases.

Consequently, in order to decrease the hydrophobicity, several ideashave been proposed, which involve the copolymerization of a methacrylicacid derivative having a lactone structure or the introduction of ahydrophilic group such as a hydroxyl group into the alicyclic structure.For example, Japanese Patent Laid-Open Nos. 10-319595, 10-274852 and thelike disclose a copolymer of a (meth)acrylic ester having an adamantaneskeleton in an ester portion thereof and a (meth)acrylic ester having alactone skeleton in an ester portion thereof. In addition, JapanesePatent Laid-Open No. 2002-82441 discloses a cycloolefin or acryliccopolymer containing a lactone structure.

However, in many cases, these acrylic resins or cycloolefin resins donot have sufficient solubility in a solvent when a resist solution isprepared. Accordingly, there may be a case where a long time is requiredfor dissolution of the resin, or the number of the steps of theproduction method is increased by the generation of an insoluble matter,so that it might affect the preparation of the resist solution.Moreover, there may also be a case where these acrylic resins orcycloolefin resins do not have sufficient heat resistance. Furthermore,when these acrylic resins or cycloolefin resins are used as a resistresin, roughness of a sidewall of a resist pattern formed by patterningwith an excimer laser and the subsequent development procedure, that is,line edge roughness might be generated, and consequently, a circuitwidth might become uneven or the circuit might be broken down, and theuse of these acrylic resins or cycloolefin resins as a resist resin maybring about the possibility of the decrease in yield during theproduction process of a semiconductor.

DISCLOSURE OF THE INVENTION

It is an object of the present invention to provide a novel monomer fromwhich a homopolymer and a copolymer being excellent in lighttransparency and heat stability are obtained, and a production methodthereof. It is another object of the present invention to provide apolymer which is excellent in light transparency and heat stability; apolymer which is excellent in solubility in an organic solvent and haslittle line edge roughness without damaging the resist performance suchas sensitivity, resolution or dry etching resistance; a resistcomposition suitable for use in deep ultraviolet excimer laserlithography, electron beam lithography and other lithographies; and amethod of forming a pattern using the resist composition.

The present invention relates to a 5-methylene-1,3-dioxolan-4-onederivative represented by the following formula (1):

wherein R¹ represents a bridged cyclic hydrocarbon group containing 4 to16 carbon atoms, or a linear or branched alkyl group containing 1 to 6carbon atoms which has a bridged cyclic hydrocarbon group containing 4to 16 carbon atoms as a substituent; R² represents a hydrogen atom, or alinear or branched alkyl group containing 1 to 6 carbon atoms; or R¹ andR² represent a bridged cyclic hydrocarbon group containing 4 to 16carbon atoms together with the carbon atom to which they are bound,

provided that the alkyl group and the bridged cyclic hydrocarbon groupmay have at least one substituent selected from a group consisting of alinear or branched alkyl group containing 1 to 6 carbon atoms which maybe optionally substituted, a hydroxy group, a carboxy group, an acylgroup containing 2 to 6 carbon atoms, an alkoxy group containing 1 to 6carbon atoms, and a carboxy group esterified with an alcohol containing1 to 6 carbon atoms.

Further, the present invention relates to a5-halo-5-methyl-1,3-dioxolan-4-one derivative represented by thefollowing formula (2):

wherein X represents a chlorine atom or a bromine atom; R¹ represents abridged cyclic hydrocarbon group containing 4 to 16 carbon atoms, or alinear or branched alkyl group containing 1 to 6 carbon atoms which hasa bridged cyclic hydrocarbon group containing 4 to 16 carbon atoms as asubstituent; R² represents a hydrogen atom, or a linear or branchedalkyl group containing 1 to 6 carbon atoms; or R¹ and R² represent abridged cyclic hydrocarbon group containing 4 to 16 carbon atomstogether with the carbon atom to which they are bound,

provided that the alkyl group and the bridged cyclic hydrocarbon groupmay have at least one substituent selected from a group consisting of alinear or branched alkyl group containing 1 to 6 carbon atoms which maybe optionally substituted, a hydroxy group, a carboxy group, an acylgroup containing 2 to 6 carbon atoms, an alkoxy group containing 1 to 6carbon atoms, and a carboxy group esterified with an alcohol containing1 to 6 carbon atoms.

Furthermore, the present invention relates to a method of producing the5-halo-5-methyl-1,3-dioxolan-4-one derivative represented by the aboveformula (2), which comprises the step of:

reacting a 5-methyl-1,3-dioxolan-4-one derivative represented by thefollowing formula (3) with a halogenating agent at a reactiontemperature within a range of 50° C. to 65° C.:

wherein R¹ represents a bridged cyclic hydrocarbon group containing 4 to16 carbon atoms, or a linear or branched alkyl group containing 1 to 6carbon atoms which has a bridged cyclic hydrocarbon group containing 4to 16 carbon atoms as a substituent; R² represents a hydrogen atom, or alinear or branched alkyl group containing 1 to 6 carbon atoms; or R¹ andR² represent a bridged cyclic hydrocarbon group containing 4 to 16carbon atoms together with the carbon atom to which they are bound,

provided that the alkyl group and the bridged cyclic hydrocarbon groupmay have at least one substituent selected from a group consisting of alinear or branched alkyl group containing 1 to 6 carbon atoms which maybe optionally substituted, a hydroxy group, a carboxy group, an acylgroup containing 2 to 6 carbon atoms, an alkoxy group containing 1 to 6carbon atoms, and a carboxy group esterified with an alcohol containing1 to 6 carbon atoms.

Moreover, the present invention relates to a method of producing the5-methylene-1,3-dioxolan-4-one derivative represented by the aboveformula (1), which comprises the step of:

reacting the 5-halo-5-methyl-1,3-dioxolan-4-one derivative representedby the above formula (2) with an amide compound represented by thefollowing formula (5) to carry out a dehydrohalogenation reaction:

wherein each of R³, R⁴ and R⁵ independently represents a hydrogen atom,or a linear or branched alkyl group containing 1 to 4 carbon atoms.

Further, the present invention relates to a method of producing the5-methylene-1,3-dioxolan-4-one derivative represented by the aboveformula (1), which comprises the step of:

reacting a 5-halomethyl-1,3-dioxolan-4-one derivative represented by thefollowing formula (4) with an amide compound represented by thefollowing formula (5) to carry out a dehydrohalogenation reaction:

wherein X represents a chlorine atom or a bromine atom; R¹ represents abridged cyclic hydrocarbon group containing 4 to 16 carbon atoms, or alinear or branched alkyl group containing 1 to 6 carbon atoms which hasa bridged cyclic hydrocarbon group containing 4 to 16 carbon atoms as asubstituent; R² represents a hydrogen atom, or a linear or branchedalkyl group containing 1 to 6 carbon atoms; or R¹ and R² represent abridged cyclic hydrocarbon group containing 4 to 16 carbon atomstogether with the carbon atom to which they are bound,

provided that the alkyl group and the bridged cyclic hydrocarbon groupmay have at least one substituent selected from a group consisting of alinear or branched alkyl group containing 1 to 6 carbon atoms which maybe optionally substituted, a hydroxy group, a carboxy group, an acylgroup containing 2 to 6 carbon atoms, an alkoxy group containing 1 to 6carbon atoms, and a carboxy group esterified with an alcohol containing1 to 6 carbon atoms; and

wherein each of R³, R⁴ and R⁵ independently represents a hydrogen atom,or a linear or branched alkyl group containing 1 to 4 carbon atoms.

Furthermore, the present invention relates to a polymer obtained by(co)polymerizing a monomer composition comprising a monomer representedby the above formula (1).

Moreover, the present invention relates to a polymer comprising at leastone of constitutional units represented by the following formula (6):

wherein R¹ represents a bridged cyclic hydrocarbon group containing 4 to16 carbon atoms, or a linear or branched alkyl group containing 1 to 6carbon atoms which has a bridged cyclic hydrocarbon group containing 4to 16 carbon atoms as a substituent; R² represents a hydrogen atom, or alinear or branched alkyl group containing 1 to 6 carbon atoms; or R¹ andR² represent a bridged cyclic hydrocarbon group containing 4 to 16carbon atoms together with the carbon atom to which they are bound,

provided that the alkyl group and the bridged cyclic hydrocarbon groupmay have at least one substituent selected from a group consisting of alinear or branched alkyl group containing 1 to 6 carbon atoms which maybe optionally substituted, a hydroxy group, a carboxy group, an acylgroup containing 2 to 6 carbon atoms, an alkoxy group containing 1 to 6carbon atoms, and a carboxy group esterified with an alcohol containing1 to 6 carbon atoms.

Further, the present invention relates to a polymer comprising at leastone of constitutional units represented by the following formula (7) andat least one of constitutional units represented by the followingformula (8), (9) or (10):

wherein each of R⁶ and R⁷ independently represents a hydrogen atom, alinear or branched alkyl group containing 1 to 6 carbon atoms, a cyclichydrocarbon group containing 4 to 16 carbon atoms, or a linear orbranched alkyl group containing 1 to 6 carbon atoms which has a cyclichydrocarbon group containing 4 to 16 carbon atoms as a substituent; orR⁶ and R⁷ represent a cyclic hydrocarbon group containing 4 to 16 carbonatoms together with the carbon atom to which they are bound,

provided that the alkyl group and the cyclic hydrocarbon group may haveat least one substituent selected from a group consisting of a linear orbranched alkyl group containing 1 to 6 carbon atoms which may beoptionally substituted, a hydroxy group, a carboxy group, an acyl groupcontaining 2 to 6 carbon atoms, an alkoxy group containing 1 to 6 carbonatoms, and a carboxy group esterified with an alcohol containing 1 to 6carbon atoms;

wherein R⁸ represents a hydrogen atom or a methyl group, and R⁹represents a linear or branched alkyl group containing 1 to 6 carbonatoms, a cyclic hydrocarbon group containing 4 to 8 carbon atoms, or abridged cyclic hydrocarbon group containing 4 to 16 carbon atoms,

provided that the alkyl group, the cyclic hydrocarbon group and thebridged cyclic hydrocarbon group may have at least one substituentselected from a group consisting of a linear or branched alkyl groupcontaining 1 to 6 carbon atoms which may be optionally substituted, ahydroxy group, a carboxy group, and a carboxy group esterified with analcohol containing 1 to 6 carbon atoms;

wherein R¹⁰ represents a hydrogen atom or a methyl group, and R¹¹represents a hydrogen atom, a hydrophilic functional group, a linear orbranched alkyl group containing 1 to 6 carbon atoms which has ahydrophilic functional group, a cyclic hydrocarbon group containing 4 to8 carbon atoms which has a hydrophilic functional group, or a bridgedcyclic hydrocarbon group containing 4 to 16 carbon atoms which has ahydrophilic functional group,

provided that the alkyl group, the cyclic hydrocarbon group, the bridgedcyclic hydrocarbon group and the hydrophilic functional group may haveat least one substituent selected from a group consisting of a linear orbranched alkyl group containing 1 to 6 carbon atoms which may beoptionally substituted, a hydroxy group, a carboxy group, and a carboxygroup esterified with an alcohol containing 1 to 6 carbon atoms; and

wherein each of R¹² and R¹³ independently represents a hydrogen atom, amethyl group or an ethyl group, and q represents an integer of 1 to 4.

It is to be noted that, in this polymer, the constitutional units (7),(8), (9) and (10) are not necessarily of the same type, but two or moretypes may be mixed therein. Moreover, in this polymer, eachconstitutional unit can have any given sequence. Accordingly, thispolymer may be a random copolymer, an alternating copolymer, or a blockcopolymer.

Further, the present invention relates to the above polymer wherein theconstitutional unit represented by the above formula (7) is theconstitutional unit represented by the above formula (6).

Furthermore, the present invention relates to a polymer comprising atleast one of constitutional units represented by the following formula(11):

wherein W¹ represents a direct bond or a methylene chain containing 1 to6 carbon atoms [—(CH₂)_(k)— (wherein k represents an integer of 0 to6)], W² represents a direct bond or a methylene chain containing 1 to 3carbon atoms [—(CH₂)_(I)— (wherein I represents an integer of 0 to 3)],W³ represents a methylene chain containing 1 to 3 carbon atoms[—(CH₂)_(m)— (wherein m represents an integer of 1 to 3)], R¹⁴represents a hydrogen atom or a methyl group, R¹⁵ represents a bridgedcyclic hydrocarbon group containing 4 to 16 carbon atoms, or a linear orbranched alkyl group containing 1 to 6 carbon atoms which has a bridgedcyclic hydrocarbon group containing 4 to 16 carbon atoms as asubstituent, R¹⁶ represents a hydrogen atom, or a linear or branchedalkyl group containing 1 to 6 carbon atoms; or R¹⁵ and R¹⁶ represent abridged cyclic hydrocarbon group containing 4 to 16 carbon atomstogether with the carbon atom to which they are bound,

provided that the methylene chain containing 1 to 6 carbon atoms may beoptionally substituted by an optionally substituted alkyl groupcontaining 1 to 3 carbon atoms, and may optionally have at least oneether bond therein, the methylene chain containing 1 to 3 carbon atomsmay have a carbonyl group therein, and the alkyl group and the bridgedcyclic hydrocarbon group may have at least one substituent selected froma group consisting of a linear or branched alkyl group containing 1 to 6carbon atoms which may be optionally substituted, a hydroxy group, acarboxy group, an acyl group containing 2 to 6 carbon atoms, an alkoxygroup containing 1 to 6 carbon atoms, and a carboxy group esterifiedwith an alcohol containing 1 to 6 carbon atoms.

Moreover, the present invention relates to a polymer comprising at leastone of constitutional units represented by the following formula (12):

wherein W⁴ represents a direct bond or a methylene chain containing 1 to6 carbon atoms [—(CH₂)_(n)— (wherein n represents an integer of 0 to6)], R¹⁷ represents a hydrogen atom or a methyl group, each of R¹⁸ andR¹⁹ independently represents a hydrogen atom, a linear or branched alkylgroup containing 1 to 6 carbon atoms, a cyclic hydrocarbon groupcontaining 4 to 16 carbon atoms, or a linear or branched alkyl groupcontaining 1 to 6 carbon atoms which has a cyclic hydrocarbon groupcontaining 4 to 16 carbon atoms as a substituent; or R¹⁸ and R¹⁹represent a cyclic hydrocarbon group containing 4 to 16 carbon atomstogether with the carbon atom to which they are bound,

provided that the methylene chain containing 1 to 6 carbon atoms may beoptionally substituted by an optionally substituted alkyl groupcontaining 1 to 3 carbon atoms, and may optionally have at least oneether bond therein, and the alkyl group and the cyclic hydrocarbon groupmay have at least one substituent selected from a group consisting of alinear or branched alkyl group containing 1 to 6 carbon atoms which maybe optionally substituted, a hydroxy group, a carboxy group, an acylgroup containing 2 to 6 carbon atoms, an alkoxy group containing 1 to 6carbon atoms, and a carboxy group esterified with an alcohol containing1 to 6 carbon atoms.

Further, the present invention relates to a polymer comprising at leastone of constitutional units represented by the following formula (13)and at least one of constitutional units represented by the aboveformula (8), (9) or (10):

wherein W⁵ represents a direct bond or a methylene chain containing 1 to6 carbon atoms [—(CH₂)_(x)— (wherein x represents an integer of 0 to6)], W⁶ represents a direct bond or a methylene chain containing 1 to 3carbon atoms [—(CH₂)_(y)— (wherein y represents an integer of 0 to 3)],W⁷ represents a methylene chain containing 1 to 3 carbon atoms[—(CH₂)_(z)— (wherein z represents an integer of 1 to 3)], R²⁰represents a hydrogen atom or a methyl group, each of R²¹ and R²²independently represents a hydrogen atom, a linear or branched alkylgroup containing 1 to 6 carbon atoms, a cyclic hydrocarbon groupcontaining 4 to 16 carbon atoms, or a linear or branched alkyl groupcontaining 1 to 6 carbon atoms which has a cyclic hydrocarbon groupcontaining 4 to 16 carbon atoms as a substituent; or R²¹ and R²²represent a cyclic hydrocarbon group containing 4 to 16 carbon atomstogether with the carbon atom to which they are bound,

provided that the methylene chain containing 1 to 6 carbon atoms may beoptionally substituted by an optionally substituted alkyl groupcontaining 1 to 3 carbon atoms, and may optionally have at least oneether bond therein, the methylene chain containing 1 to 3 carbon atomsmay have a carbonyl group therein, and the alkyl group and the cyclichydrocarbon group may have at least one substituent selected from agroup consisting of a linear or branched alkyl group containing 1 to 6carbon atoms which may be optionally substituted, a hydroxy group, acarboxy group, an acyl group containing 2 to 6 carbon atoms, an alkoxygroup containing 1 to 6 carbon atoms, and a carboxy group esterifiedwith an alcohol containing 1 to 6 carbon atoms.

It is to be noted that, in this polymer, the constitutional units (13),(8), (9) and (10) are not necessarily of the same type, but two or moretypes may be mixed therein. Moreover, in this polymer, eachconstitutional unit can have any given sequence. Accordingly, thispolymer may be a random copolymer, an alternating copolymer, or a blockcopolymer.

Further, the present invention relates to the above polymer wherein theconstitutional unit represented by the above formula (13) is theconstitutional unit represented by the above formula (11) or (12).

Furthermore, the present invention relates to the above polymer whereinits mass-average molecular weight is within a range of 1,000 to 100,000.

Moreover, the present invention relates to a polymer mixture comprisingat least one polymer described above, and at least one polymercomprising at least one of constitutional units represented by the aboveformula (8), (9) or (10).

Further, the present invention relates to a resist composition, whichcomprises at least one polymer comprising at least one of constitutionalunits represented by the above formula (7).

Furthermore, the present invention relates to a resist composition,which comprises at least one polymer comprising at least one ofconstitutional units represented by the above formula (13).

Moreover, the present invention relates to a resist composition, whichcomprises at least one polymer described above or the above polymermixture.

Further, the present invention relates to a resist composition, whichcomprises at least one polymer described above or the above polymermixture, and a photoacid generator.

Furthermore, the present invention relates to a method of forming apattern, which comprises the steps of:

coating the above resist composition onto a substrate to be processed;

exposing the substrate to a light with a wavelength of 250 nm or shorteror an electron beam; and

development.

Moreover, the present invention relates to a method of forming apattern, which comprises the steps of:

coating the above resist composition onto a substrate to be processed;

exposing the substrate to a light with a wavelength of 250 nm or shorteror an electron beam; and

developing it with a developing solution after subjecting it to a heattreatment, if necessary.

The term “(co)polymerization” is used herein to mean eitherhomopolymerization or copolymerization, as it is commonly used.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a ¹H-NMR spectrum of the compound represented by a formula(19), which was obtained in Example 1.

FIG. 2 is a ¹³C-NMR spectrum of the compound represented by the formula(19), which was obtained in Example 1.

FIG. 3 is a ¹H-NMR spectrum of the compound represented by a formula(21), which was obtained in Example 2.

FIG. 4 is a ¹³C-NMR spectrum of the compound represented by the formula(21), which was obtained in Example 2.

FIG. 5 is a ¹H-NMR spectrum of the compound represented by a formula(23), which was obtained in Example 3.

FIG. 6 is a ¹³C-NMR spectrum of the compound represented by the formula(23), which was obtained in Example 3.

BEST MODE FOR CARRYING OUT THE INVENTION

The compound of the present invention comprising a5-methylene-1,3-dioxolan-4-one structure is a5-methylene-1,3-dioxolan-4-one derivative represented by the aboveformula (1). The 5-methylene-1,3-dioxolan-4-one derivative of thepresent invention is a novel compound having, at position 2, asubstituent having a bridged cyclic hydrocarbon structure. Thisderivative is particularly useful in that a homopolymer or a copolymerobtained by (co)polymerization of this monomer is excellent in lighttransparency and heat stability. Moreover, the5-methylene-1,3-dioxolan-4-one derivative of the present invention isexcellent in stability, moderate polarity and solubility in varioussolvents, and exhibits acid decomposition properties. Its polymer canalso be expected to be excellent in stability, moderate polarity andsolubility in various solvents, and to exhibit acid decompositionproperties. Accordingly, the 5-methylene-1,3-dioxolan-4-one derivativeof the present invention can be widely used as a raw material monomerfor a component resin of a coating material, an adhesive, anagglutinant, a resin for ink, a resist, or the like.

Such a 5-methylene-1,3-dioxolan-4-one derivative of the presentinvention can be easily produced with a high yield and a high purity byreacting the 5-halo-5-methyl-1,3-dioxolan-4-one derivative representedby the above formula (2), which can be obtained by reacting the5-methyl-1,3-dioxolan-4-one derivative represented by the above formula(3) with a halogenating agent at a reaction temperature within a rangeof 50° C. to 65° C., or the 5-halomethyl-1,3-dioxolan-4-one derivativerepresented by the above formula (4), with the amide compoundrepresented by the above formula (5) to carry out a dehydrohalogenationreaction.

Moreover, the first polymer of the invention is obtained by(co)polymerizing a monomer composition comprising the monomerrepresented by the above formula (1), and comprises a monomer unitwherein the unsaturated bond of the monomer represented by the aboveformula (1) is open-chained (transfer of electrons), that is, theconstitutional unit represented by the above formula (6). The monomerrepresented by the above formula (1) may be a single type or a mixtureof two or more types.

Furthermore, the second polymer of the invention comprises at least oneof constitutional units represented by the above formula (7) and atleast one of constitutional units represented by the above formula (8),(9) or (10). The constitutional units (7), (8), (9) and (10) are notnecessarily of the same type, but two or more types may be mixedtherein. The constitutional unit represented by the above formula (7) ispreferably the constitutional unit represented by the above formula (6).

Still further, the third polymer of the invention comprises at least oneof constitutional units represented by the above formula (11). Theconstitutional unit (11) is not necessarily of the same type, but two ormore types may be mixed therein.

Still further, the fourth polymer of the invention comprises at leastone of constitutional units represented by the above formula (12). Theconstitutional unit (12) is not necessarily of the same type, but two ormore types may be mixed therein.

Still further, the fifth polymer of the invention comprises at least oneof constitutional units represented by the above formula (13) and atleast one of constitutional units represented by the above formula (8),(9) or (10). The constitutional units (13), (8), (9) and (10) are notnecessarily of the same type, but two or more types may be mixedtherein. The constitutional unit represented by the above formula (13)is preferably the constitutional unit represented by the above formula(11) or (12).

In all of the above first to fifth polymers of the invention, eachconstitutional unit can have any given sequence. Accordingly, thesepolymers may be a random copolymer, an alternating copolymer, or a blockcopolymer.

The polymer of the present invention is excellent in solubility in anorganic solvent (resist solvent) and heat resistance, and has littleline edge roughness, while maintaining its resist performance such assensitivity, resolution and dry etching resistance. The polymer of thepresent invention is particularly preferable as a resist resin used indeep ultraviolet excimer laser lithography, electron beam lithography,and other lithographies.

Hereinafter, the present invention will be described in detail.

1. 5-methylene-1,3-dioxolan-4-one derivative of the Present Invention

First, a 5-methylene-1,3-dioxolan-4-one derivative represented by thefollowing formula (1) will be explained:

In formula (1), R¹ represents a bridged cyclic hydrocarbon groupcontaining 4 to 16 carbon atoms, or a linear or branched alkyl groupcontaining 1 to 6 carbon atoms which has a bridged cyclic hydrocarbongroup containing 4 to 16 carbon atoms as a substituent; R² represents ahydrogen atom, or a linear or branched alkyl group containing 1 to 6carbon atoms; or R¹ and R² represent a bridged cyclic hydrocarbon groupcontaining 4 to 16 carbon atoms together with the carbon atom to whichthey are bound.

Herein, the alkyl group and the bridged cyclic hydrocarbon group may beunsubstituted, or may have at least one substituent selected from agroup consisting of a linear or branched alkyl group containing 1 to 6carbon atoms which may be optionally substituted, a hydroxy group, acarboxy group, an acyl group containing 2 to 6 carbon atoms, an alkoxygroup containing 1 to 6 carbon atoms, and a carboxy group esterifiedwith an alcohol containing 1 to 6 carbon atoms. When the alkyl group andthe bridged cyclic hydrocarbon group have two or more substituents, thesubstituents may be of either a single type, or two or more types.

Examples of a substituent on the linear or branched alkyl groupcontaining 1 to 6 carbon atoms that is the substituent on the alkylgroup and the bridged cyclic hydrocarbon group may include a hydroxygroup, a carboxy group, an acyl group containing 1 to 6 carbon atoms,and an amino group. The number of substituents may be either one, or twoor more. When the above group has two or more substituents, thesubstituents may be of either a single type, or two or more types.

The bridged cyclic hydrocarbon group is a group having a structurerepresented by the following formula (15) or (16) including adamantaneand norbornane as typical examples:

wherein each of A¹ and B¹ represents a linear or branched alkylenegroup, and A¹ and B¹ may be identical or may be different; or

wherein each of A², B² and L represents a linear or branched alkylenegroup, and A², B² and L may be identical or may be different.

Examples of R¹ in the above formula (1) may include bridged cyclichydrocarbon groups such as a 2-norbornyl group, 1-adamantyl group,1-adamantanemethyl group, 1-adamantaneethyl group, 2-adamantyl group,2-adamantanemethyl group, 2-adamantaneethyl group or 2-adamantanonylgroup. Moreover, R¹ may include a structure wherein these groups aresubstituted with at least one substituent selected from a groupconsisting of a linear or branched alkyl group containing 1 to 6 carbonatoms which may be optionally substituted (e.g., a hydroxy group, acarboxy group, a carboxy group esterified with an alcohol containing 1to 6 carbon atoms, an acyl group containing 1 to 6 carbon atoms, anamino group, and the like), a hydroxy group, a carboxy group, an acylgroup containing 2 to 6 carbon atoms, an alkoxy group containing 1 to 6carbon atoms, and a carboxy group esterified with an alcohol containing1 to 6 carbon atoms, or the like. The number of substituents may beeither one, or two or more. When the above group has two or moresubstituents, the substituents may be of either a single type, or two ormore types.

Of these, in terms of having excellent dry etching resistance when thepolymer is used for a resist composition, a 2-norbornyl group, a1-adamantyl group, a 1-adamantanemethyl group, a 1-adamantaneethylgroup, a 2-adamantyl group, a 2-adamantanemethyl group and a2-adamantaneethyl group are preferable as R¹. In terms of the lighttransparency and heat stability such as a glass transition temperature(Tg) of the (co)polymer to be obtained, a 1-adamantyl group and a2-norbornyl group are more preferable as R¹.

Examples of R² in the above formula (1) may include a hydrogen atom, amethyl group, an ethyl group, a propyl group, an isopropyl group, abutyl group, and a tert-butyl group. Moreover, R² may include astructure wherein these groups are substituted with at least onesubstituent selected from a group consisting of a linear or branchedalkyl group containing 1 to 6 carbon atoms which may be optionallysubstituted (e.g., a hydroxy group, a carboxy group, a carboxy groupesterified with an alcohol containing 1 to 6 carbon atoms, an acyl groupcontaining 1 to 6 carbon atoms, an amino group, and the like), a hydroxygroup, a carboxy group, an acyl group containing 2 to 6 carbon atoms, analkoxy group containing 1 to 6 carbon atoms, and a carboxy groupesterified with an alcohol containing 1 to 6 carbon atoms, or the like.The number of substituents may be either one, or two or more. When theabove group has two or more substituents, the substituents may be ofeither a single type, or two or more types.

Of these, a methyl group and an ethyl group are preferable as R², interms of having excellent coatability when the polymer is used for aresist composition.

Further, R¹ and R² in the above formula (1) may form a bridged cyclichydrocarbon structure containing 4 to 16 carbon atoms, together with thecarbon atom to which they are bound. Examples of such a derivativerepresented by the above formula (1) may includespiro[norbornan-2,2′-(5′-methylene-1′,3′-dioxolan-4′-one) andspiro[adamantan-2,2′-(5′-methylene-1′,3′-dioxolan-4′-one). Furthermore,examples of such a derivative may also include those wherein the bridgedcyclic hydrocarbon structure containing 4 to 16 carbon atoms issubstituted with at least one substituent selected from a groupconsisting of a linear or branched alkyl group containing 1 to 6 carbonatoms which may be optionally substituted (e.g., a hydroxy group, acarboxy group, a carboxy group esterified with an alcohol containing 1to 6 carbon atoms, an acyl group containing 1 to 6 carbon atoms, anamino group, and the like), a hydroxy group, a carboxy group, an acylgroup containing 2 to 6 carbon atoms, an alkoxy group containing 1 to 6carbon atoms, and a carboxy group esterified with an alcohol containing1 to 6 carbon atoms, or the like. The number of substituents may beeither one, or two or more. When the above group has two or moresubstituents, the substituents may be of either a single type, or two ormore types.

Preferred examples of the 5-methylene-1,3-dioxolan-4-one derivativerepresented by the above formula (1) may include5-methylene-2-(1-adamantyl)-2-methyl-1,3-dioxolan-4-one,5-methylene-2-(2-adamantyl)-2-methyl-1,3-dioxolan-4-one,5-methylene-2-methyl-2-(2-norbornyl)-1,3-dioxolan-4-one,5-methylene-2-(1-adamantanemethyl)-2-methyl-1,3-dioxolan-4-one,5-methylene-2-(2-adamantanemethyl)-2-methyl-1,3-dioxolan-4-one,5-methylene-2-(1-adamantaneethyl)-2-methyl-1,3-dioxolan-4-one,5-methylene-2-(2-adamantaneethyl)-2-methyl-1,3-dioxolan-4-one,5-methylene-2-(1-adamantyl)-2-ethyl-1,3-dioxolan-4-one,5-methylene-2-(2-adamantyl)-2-ethyl-1,3-dioxolan-4-one,5-methylene-2-ethyl-2-(2-norbornyl)-1,3-dioxolan-4-one,5-methylene-2-(1-adamantanemethyl)-2-ethyl-1,3-dioxolan-4-one,5-methylene-2-(2-adamantanemethyl)-2-ethyl-1,3-dioxolan-4-one,5-methylene-2-(1-adamantaneethyl)-2-ethyl-1,3-dioxolan-4-one,5-methylene-2-(2-adamantaneethyl)-2-ethyl-1,3-dioxolan-4-one, and thelike.

As stated above, in the above compounds, an alkyl group and/or a bridgedcyclic hydrocarbon group may be substituted with a linear or branchedalkyl group containing 1 to 6 carbon atoms which may be optionallysubstituted (e.g., a hydroxy group, a carboxy group, a carboxy groupesterified with an alcohol containing 1 to 6 carbon atoms, an acyl groupcontaining 1 to 6 carbon atoms, an amino group, and the like), a hydroxygroup, a carboxy group, an acyl group containing 2 to 6 carbon atoms, analkoxy group containing 1 to 6 carbon atoms, a carboxy group esterifiedwith an alcohol containing 1 to 6 carbon atoms, or the like. The numberof substituents may be either one, or two or more. When the abovecompound has two or more substituents, the substituents may be of eithera single type, or two or more types.

Of these, a linear or branched alkyl group containing 1 to 6 carbonatoms which may be optionally substituted, a hydroxy group, a carboxygroup, an acyl group containing 2 to 6 carbon atoms, an alkoxy groupcontaining 1 to 6 carbon atoms, and a carboxy group esterified with analcohol containing 1 to 6 carbon atoms are preferable as a substituent,in terms of having excellent light transparency when the polymer is usedfor a resist composition. Moreover, in terms of having excellent dryetching resistance when the polymer is used for a resist composition, amethyl group and an ethyl group are more preferable as a substituent.And, in terms of having excellent adhesion of the polymer to a substratewhen the polymer is used for a resist composition, a hydroxyl group, ahydroxymethyl group, and a hydroxyethyl group are more preferable as asubstituent.

2. 5-halo-5-methyl-1,3-dioxolan-4-one derivative of the PresentInvention

Next, a 5-halo-5-methyl-1,3-dioxolan-4-one derivative represented by thefollowing formula (2) will be explained, which will be an intermediatewhen the 5-methylene-1,3-dioxolan-4-one derivative represented by theabove formula (1) is produced:

In formula (2), X represents a chlorine atom or a bromine atom; R¹represents a bridged cyclic hydrocarbon group containing 4 to 16 carbonatoms, or a linear or branched alkyl group containing 1 to 6 carbonatoms which has a bridged cyclic hydrocarbon group containing 4 to 16carbon atoms as a substituent; R² represents a hydrogen atom, or alinear or branched alkyl group containing 1 to 6 carbon atoms; or R¹ andR² represent a bridged cyclic hydrocarbon group containing 4 to 16carbon atoms together with the carbon atom to which they are bound.

Herein, the alkyl group and the bridged cyclic hydrocarbon group may beunsubstituted, or may have at least one substituent selected from agroup consisting of a linear or branched alkyl group containing 1 to 6carbon atoms which may be optionally substituted, a hydroxy group, acarboxy group, an acyl group containing 2 to 6 carbon atoms, an alkoxygroup containing 1 to 6 carbon atoms, and a carboxy group esterifiedwith an alcohol containing 1 to 6 carbon atoms. When the alkyl group andthe bridged cyclic hydrocarbon group have two or more substituents, thesubstituents may be of either a single type, or two or more types.

R¹ and R² in the formula (2) correspond to R¹ and R² in the formula (1),respectively. Accordingly, the R¹ and R² in the formula (2) are the sameas the R¹ and R² in the formula (1), and preferred examples of R¹ and R²in the formula (2) are also the same as the preferred examples of R¹ andR² in the formula (1).

Moreover, a bromine atom is preferable as X in the above formula (2)because when the derivative is converted into the5-methylene-1,3-dioxolan-4-one derivative represented by the aboveformula (1), the reaction more smoothly progresses.

3. Production method of the 5-halo-5-methyl-1,3-dioxolan-4-onederivative of the Present Invention

Next, a method of producing the 5-halo-5-methyl-1,3-dioxolan-4-onederivative represented by the above formula (2) of the present inventionwill be explained.

The 5-halo-5-methyl-1,3-dioxolan-4-one derivative represented by theabove formula (2) can be produced by reacting a5-methyl-1,3-dioxolan-4-one derivative represented by the followingformula (3) as a raw material with a halogenating agent, so that theposition 5 of the above derivative is halogenated:

In formula (3), R¹ represents a bridged cyclic hydrocarbon groupcontaining 4 to 16 carbon atoms, or a linear or branched alkyl groupcontaining 1 to 6 carbon atoms which has a bridged cyclic hydrocarbongroup containing 4 to 16 carbon atoms as a substituent; R² represents ahydrogen atom, or a linear or branched alkyl group containing 1 to 6carbon atoms; or R¹ and R² represent a bridged cyclic hydrocarbon groupcontaining 4 to 16 carbon atoms together with the carbon atom to whichthey are bound.

Herein, the alkyl group and the bridged cyclic hydrocarbon group may beunsubstituted, or may have at least one substituent selected from agroup consisting of a linear or branched alkyl group containing 1 to 6carbon atoms which may be optionally substituted, a hydroxy group, acarboxy group, an acyl group containing 2 to 6 carbon atoms, an alkoxygroup containing 1 to 6 carbon atoms, and a carboxy group esterifiedwith an alcohol containing 1 to 6 carbon atoms. When the alkyl group andthe bridged cyclic hydrocarbon group have two or more substituents, thesubstituents may be of either a single type, or two or more types.

R¹ and R² in the formula (3) correspond to R¹ and R² in the formula (2),respectively. Accordingly, the R¹ and R² in the formula (3) are the sameas the R¹ and R² in the formula (2), and preferred examples of R¹ and R²in the formula (3) are also the same as the preferred examples of R¹ andR² in the formula (2). That is to say, the R¹ and R² in the formula (3)are the same as the R¹ and R² in the formula (1), and preferred examplesof R¹ and R² in the formula (3) are also the same as the preferredexamples of R¹ and R² in the formula (1).

I. Production Method of the Derivative Represented by the Above Formula(3), Which is a raw Material

The 5-methyl-1,3-dioxolan-4-one derivative represented by the aboveformula (3) that is a raw material can be synthesized from the ketone oraldehyde represented by the following formula (17) by a known method:

wherein R¹ and R² correspond to R¹ and R² in the formula (3),respectively.

That is to say, in the above formula (17), R¹ represents a bridgedcyclic hydrocarbon group containing 4 to 16 carbon atoms, or a linear orbranched alkyl group containing 1 to 6 carbon atoms which has a bridgedcyclic hydrocarbon group containing 4 to 16 carbon atoms as asubstituent; R² represents a hydrogen atom, or a linear or branchedalkyl group containing 1 to 6 carbon atoms; or R¹ and R² represent abridged cyclic hydrocarbon group containing 4 to 16 carbon atomstogether with the carbon atom to which they are bound.

Herein, the alkyl group and the bridged cyclic hydrocarbon group mayhave at least one substituent selected from a group consisting of alinear or branched alkyl group containing 1 to 6 carbon atoms which maybe optionally substituted, a hydroxy group, a carboxy group, an acylgroup containing 2 to 6 carbon atoms, an alkoxy group containing 1 to 6carbon atoms, and a carboxy group esterified with an alcohol containing1 to 6 carbon atoms.

The 5-methyl-1,3-dioxolan-4-one derivative represented by the aboveformula (3) can be synthesized, for example, by reacting the compoundrepresented by the above formula (17) with a lactic acid or an esterthereof, the reaction being accompanied with dehydration ordealcoholization. This addition reaction is preferably carried out at areaction temperature within a range of 20° C. to a reflux temperatureunder conditions in which either the compound represented by the aboveformula (17), or a lactic acid or an ester thereof is in an excessiveamount. The addition reaction can sufficiently progress with acidity oflactic acid, but an acid catalyst such as a Lewis acid may be used.Moreover, the addition reaction may be carried out with no solvents, orit may be carried out in a two-phase system containing an organicsolvent and a lactic acid, using a nonpolar organic solvent. Theaddition reaction can be carried out in either a homogeneous system, ora heterogeneous system.

Furthermore, the 5-methyl-1,3-dioxolan-4-one derivative represented bythe above formula (3) can also be synthesized by reacting the compoundrepresented by the above formula (17) with a orthoformic acid trimethylester to obtain a dimethoxy form or an enol ether form, and thenconducting a reaction of the obtained compound with a lactic acid, thereaction being accompanied with demethanolation. The reaction betweenthe dimethoxy form and the lactic acid is preferably carried out at areaction temperature within a range of 20° C. to a reflux temperatureunder conditions in which either the dimethoxy form or the enol etherform, or the lactic acid is in an excessive amount. This reaction cansufficiently progress with acidity of lactic acid, but an acid catalystsuch as a Lewis acid is preferably used. Moreover, this reaction may becarried out with no solvents, or it may be carried out in a two-phasesystem containing an organic solvent and a lactic acid, using a nonpolarorganic solvent. The reaction can be carried out in either a homogeneoussystem, or a heterogeneous system.

Examples of a pattern of the reaction may include a closed system inwhich the reaction is carried out under reduced pressure, under ordinarypressure or under increased pressure, using a well-closed container; anda reflux system in which the reaction is carried out at a boiling pointor lower and a volatilized raw material, product and solvent arerefluxed with a condenser. These reactions are preferably carried outusing a Dienstark or a decanter to remove the generated water or alcoholto the outside of the system.

Moreover, an optically active lactic acid can also be used in thereaction to form the derivative represented by the above formula (3). Inthis case, the obtained derivative represented by the above formula (3)has optical activity that is derived from the raw material.

II. Production Method of the Derivative Represented by the Above Formula(2)

As stated above, the 5-halo-5-methyl-1,3-dioxolan-4-one derivativerepresented by the above formula (2) can be produced by reacting the5-methyl-1,3-dioxolnae-4-one derivative represented by the above formula(3) with a halogenating agent at a reaction temperature within a rangeof 50° C. to 65° C.

Examples of a halogenating agent used in the above reaction may includeN-chlorosuccinimide, 1,3-dichloro-5,5-dimethylhydantoin,bromotrichloromethane, N-bromosuccinimide,1,3-dibromo-5,5-dimethylhydantoin, and bromine. Such a halogenatingagent may be used singly or in combination of two or more types. Ofthese, in terms of reactivity and selectivity of a position to behalogenated, N-bromosuccinimide is particularly preferably used.

In terms of yield, the use amount of a halogenating agent is preferably0.1 mole or more, more preferably 0.5 mole or more, and particularlypreferably 1 mole or more based on 1 mole of the derivative representedby the formula (3). In addition, in terms of prevention of adecomposition reaction, the use amount of a halogenating agent ispreferably 10 mole or less, more preferably 2 mole or less, andparticularly preferably 1.5 mole or less based on 1 mole of thederivative represented by the formula (3).

A radical generator such as azobisisobutyronitrile may be used in theconventional halogenation reaction. However, in the halogenationreaction of the present invention, the reaction sufficiently progresseswithout using such a radical generator. In the present invention, in thecase of using a radical generator, the use amount of the radicalgenerator is usually 0.1 mole or less based on 1 mole of the derivativerepresented by the formula (3). However, so as to reduce impuritiespassed into the next step, it is preferably 0.01 mole or less based on 1mole of the derivative represented by the formula (3).

An organic solvent is preferably used in the present halogenationreaction. Any organic solvent can be used as long as it is used in ahalogenation reaction. Examples of an organic solvent used herein mayinclude pentane, hexane, heptane, cyclopentane, cyclohexane, diethylether, diisopropyl ether, methyl-tert-butyl ether, tetrahydrofuran,carbon tetrachloride, chloroform, and methylene chloride. Such anorganic solvent may be used singly or in combination of two or moretypes. Of these, in terms of smooth progression of the reaction, hexane,heptane, cyclohexane, carbon tetrachloride or the like are preferablyused.

In terms of smooth progression of the reaction and suppression ofgeneration of by-products, the use amount of an organic solvent ispreferably 0.1 time by mass or more, more preferably 0.5 time by mass ormore, and particularly preferably 1 time by mass or more based on thederivative represented by the formula (3). In addition, in terms ofreaction rate and the amount of the waste solvent, the use amount of anorganic solvent is preferably 100 times by mass or less, more preferably50 times by mass or less, and particularly preferably 20 times by massor less based on the derivative represented by the formula (3).

Water may be contained in such an organic solvent, however, in terms ofprevention of a decomposition reaction and a side reaction, it is morepreferable that water is contained in the organic solvent in a smallamount.

The reaction temperature is generally set within a range of 50° C. to65° C. In terms of reaction rate, the reaction temperature is preferably55° C. or higher. In addition, in terms of prevention of a decompositionreaction, the reaction temperature is preferably 60° C. or lower.

Conventionally, when a halogenation reaction using a halogenating agentprogresses radically, the reaction is generally carried out around 80°C. at which a radical is likely to generate. At such a temperature,however, the decomposition reaction of a raw material and a halideprogresses significantly, resulting in a significant decrease in theyield of the derivative represented by the above formula (2). Thisdecomposition reaction particularly progresses significantly, when asubstituent bound to position 2 has a bridged cyclic hydrocarbonstructure. The inventors have found that the halogenation reaction ofthe present invention progresses even if the reaction temperature is setto 65° C. or lower at which the reaction is not conventionally carriedout, and that the decomposition reaction of a raw material and a halideonly slightly progresses at this temperature.

Examples of a pattern of the halogenation reaction may include a closedsystem in which the reaction is carried out under reduced pressure,under ordinary pressure or under increased pressure, using a well-closedcontainer; and a reflux system in which the reaction is carried out at aboiling point or lower and a volatilized raw material, product andsolvent are refluxed with a condenser.

The reaction time may be determined, taking into consideration thereaction temperature or the like. Generally, the reaction time ispreferably about 1 to 48 hours.

In the present invention, a halogenation reaction is carried out asdescribed above, so as to produce the derivative represented by theabove formula (2). In the present reaction, the product of interest canbe obtained at a good yield while sufficiently preventing a sidereaction. Accordingly, the obtained derivative represented by the aboveformula (2) can be directly used in the following dehydrohalogenationreaction. Otherwise, an unreacted halide (e.g., N-bromosuccinimide) anda by-product (e.g., succinimide) are removed from the reaction solutionby filtration, and the residue may be used in the dehydrohalogenationreaction. If necessary, removal of a solvent or exchange of a solventmay be carried out. Moreover, the obtained derivative represented by theabove formula (2) may be purified by a known method such as washing withan alkaline aqueous solution, extraction with an organic solvent/watersystem, solvent fractionation, column chromatography, or vacuumdistillation.

Where R¹ differs from R² in the derivative represented by the aboveformula (2), the carbon atom at position 2 becomes an asymmetric carbon,and optical isomers exist. These optical isomers can be isolated by aknown optical resolution method such as preferential crystallizationmethod or the use of an optical resolution column. These opticallyactive substances may be either an (R)-form or a (S)-form, or may be amixture of the (R)-form and the (S)-form, and all of these substancescan be used in the following dehydrohalogenation reaction.

4. Production method of the 5-methylene-1,3-dioxolan-4-one derivative ofthe Present Invention

Next, a method of producing the 5-methylene-1,3-dioxolan-4-onederivative represented by the above formula (1) of the present inventionwill be explained.

The 5-methylene-1,3-dioxolan-4-one derivative represented by the aboveformula (1) can be produced by reacting the5-halo-5-methyl-1,3-dioxolan-4-one derivative represented by the aboveformula (2) or a 5-halomethyl-1,3-dioxolan-4-one derivative representedby the following formula (4) with an amide compound represented by thefollowing formula (5) so as to carry out a dehydrohalogenation reaction:

wherein X represents a chlorine atom or a bromine atom; R¹ represents abridged cyclic hydrocarbon group containing 4 to 16 carbon atoms, or alinear or branched alkyl group containing 1 to 6 carbon atoms which hasa bridged cyclic hydrocarbon group containing 4 to 16 carbon atoms as asubstituent; R² represents a hydrogen atom, or a linear or branchedalkyl group containing 1 to 6 carbon atoms; or R¹ and R² represent abridged cyclic hydrocarbon group containing 4 to 16 carbon atomstogether with the carbon atom to which they are bound,

provided that the alkyl group and the bridged cyclic hydrocarbon groupmay have at least one substituent selected from a group consisting of alinear or branched alkyl group containing 1 to 6 carbon atoms which maybe optionally substituted, a hydroxy group, a carboxy group, an acylgroup containing 2 to 6 carbon atoms, an alkoxy group containing 1 to 6carbon atoms, and a carboxy group esterified with an alcohol containing1 to 6 carbon atoms; and

wherein each of R³, R⁴ and R⁵ independently represents a hydrogen atom,or a linear or branched alkyl group containing 1 to 4 carbon atoms.

I. 5-halomethyl-1,3-dioxolan-4-one derivative Represented by the AboveFormula (4)

In the above formula (4), X represents a chlorine atom or a bromineatom; R¹ represents a bridged cyclic hydrocarbon group containing 4 to16 carbon atoms, or a linear or branched alkyl group containing 1 to 6carbon atoms which has a bridged cyclic hydrocarbon group containing 4to 16 carbon atoms as a substituent; R² represents a hydrogen atom, or alinear or branched alkyl group containing 1 to 6 carbon atoms; or R¹ andR² represent a bridged cyclic hydrocarbon group containing 4 to 16carbon atoms together with the carbon atom to which they are bound.

Herein, the alkyl group and the bridged cyclic hydrocarbon group may beunsubstituted, or may have at least one substituent selected from agroup consisting of a linear or branched alkyl group containing 1 to 6carbon atoms which may be optionally substituted, a hydroxy group, acarboxy group, an acyl group containing 2 to 6 carbon atoms, an alkoxygroup containing 1 to 6 carbon atoms, and a carboxy group esterifiedwith an alcohol containing 1 to 6 carbon atoms. When the alkyl group andthe bridged cyclic hydrocarbon group have two or more substituents, thesubstituents may be of either a single type, or two or more types.

R¹ and R² in the formula (4) correspond to R¹ and R² in the formula (1),respectively. Accordingly, the R¹ and R² in the formula (4) are the sameas the R¹ and R² in the formula (1), and preferred examples of R¹ and R²in the formula (4) are also the same as the preferred examples of R¹ andR² in the formula (1).

Moreover, a bromine atom is preferable as X in the above formula (4)because when the derivative is converted into the5-methylene-1,3-dioxolan-4-one derivative represented by the aboveformula (1), the reaction more smoothly progresses.

The 5-halomethyl-1,3-dioxolan-4-one derivative represented by the aboveformula (4) can be synthesized from the ketone or aldehyde representedby the following formula (17) by a known method:

wherein R¹ and R² correspond to R¹ and R² in the formula (4),respectively.

That is to say, in the above formula (17), R¹ represents a bridgedcyclic hydrocarbon group containing 4 to 16 carbon atoms, or a linear orbranched alkyl group containing 1 to 6 carbon atoms which has a bridgedcyclic hydrocarbon group containing 4 to 16 carbon atoms as asubstituent; R² represents a hydrogen atom, or a linear or branchedalkyl group containing 1 to 6 carbon atoms; or R¹ and R² represent abridged cyclic hydrocarbon group containing 4 to 16 carbon atomstogether with the carbon atom to which they are bound.

Herein, the alkyl group and the bridged cyclic hydrocarbon group mayhave at least one substituent selected from a group consisting of alinear or branched alkyl group containing 1 to 6 carbon atoms which maybe optionally substituted, a hydroxy group, a carboxy group, an acylgroup containing 2 to 6 carbon atoms, an alkoxy group containing 1 to 6carbon atoms, and a carboxy group esterified with an alcohol containing1 to 6 carbon atoms.

The 5-halomethyl-1,3-dioxolan-4-one derivative represented by the aboveformula (4) can be synthesized, for example, by reacting the compoundrepresented by the above formula (17) with β-halolactic acid such asβ-bromolactic acid or β-chlorolactic acid, or an ester thereof. Thisreaction is preferably carried out at a reaction temperature within arange of 20° C. to a reflux temperature under conditions in which eitherthe compound represented by the above formula (17), or a β-halolacticacid or an ester thereof is in an excessive amount. This reaction ispreferably carried out using an acid catalyst such as a Lewis acid. Whenβ-halolactic acid is used, however, the reaction can sufficientlyprogress with its acidity. Moreover, the reaction may be carried outwith no solvents, or it may be carried out using a nonpolar organicsolvent. The reaction can be carried out in either a homogeneous system,or a heterogeneous system.

Furthermore, the 5-halomethyl-1,3-dioxolan-4-one derivative representedby the above formula (4) can also be synthesized by reacting thecompound represented by the above formula (17) with a orthoformic acidtrimethyl ester to obtain a dimethoxy form or an enol ether form, andthen reacting the obtained compound with a β-halolactic acid. Thereaction between the dimethoxy form and the β-halolactic acid ispreferably carried out at a reaction temperature within a range of 20°C. to a reflux temperature under conditions in which either thedimethoxy form or the enol ether form, or the β-halolactic acid is in anexcessive amount. This reaction is preferably carried out using an acidcatalyst such as a Lewis acid. When β-halolactic acid is used, however,the reaction can sufficiently progress with its acidity. Moreover, thisreaction may be carried out with no solvents, or it may be carried outusing a nonpolar organic solvent. The reaction can be carried out ineither a homogeneous system, or a heterogeneous system.

Examples of a pattern of the reaction may include a closed system inwhich the reaction is carried out under reduced pressure, under ordinarypressure or under increased pressure, using a well-closed container; anda reflux system in which the reaction is carried out at a boiling pointor lower and a volatilized raw material, product and solvent arerefluxed with a condenser. These reactions are preferably carried outusing a Dienstark or a decanter to remove the generated water or alcoholto the outside of the system.

Moreover, an optically active β-halolactic acid, ketone or aldehyde canalso be used in the reaction to form the derivative represented by theabove formula (4). In this case, the obtained derivative represented bythe above formula (4) has optical activity that is derived from the rawmaterial.

Furthermore, a racemic mixture may also be used. In this case, theobtained derivative represented by the above formula (4) becomes aracemic mixture.

Where R¹ differs from R² in the derivative represented by the aboveformula (4), the carbon atom at position 2 becomes an asymmetric carbon,and optical isomers exist. These optical isomers can be isolated by aknown optical resolution method such as the preferential crystallizationmethod or the use of an optical resolution column. These opticallyactive substances may be either an (R)-form or a (S)-form, or may be amixture of the (R)-form and the (S)-form, and all of these substancescan be used.

II. Production method of the 5-methylene-1,3-dioxolane-4-one derivativeof the Present Invention

As stated above, the 5-methylene-1,3-dioxolan-4-one derivativerepresented by the above formula (1) can be produced by reacting the5-halo-5-methyl-1,3-dioxolnae-4-one derivative represented by the aboveformula (2) or the 5-halomethyl-1,3-dioxolan-4-one derivativerepresented by the above formula (4) with the amide compound representedby the above formula (5) so as to carry out a dehydrohalogenationreaction.

Conventionally, a base has been used in such a dehydrohalogenationreaction. Representative examples of such a base may include: alkalimetal hydroxides such as lithium hydroxide, sodium hydroxide orpotassium hydroxide; alkali metal alkoxides such as sodium methoxide,sodium ethoxide, sodium-tert-butoxide or potassium-tert-butoxide; alkalimetal carboxylates such as sodium acetate; and amines such astrimethylamine, triethylamine, trioctylamine, pyridine, collidine,1,5-diazabicyclo[4.3.0]-5-nonene, 1,8-diazabicyclo[5.4.0]-7-undecene or1,4-diazabicyclo[2.2.2]octane. However, when the dehydrohalogenationreaction of the derivative represented by the above formula (2) or thederivative represented by the above formula (4) is conducted using thesebases, a decomposition reaction progresses, and thus, little derivativerepresented by the above formula (1) of interest can be obtained.Moreover, when these bases are used, there may be problems in that thereaction solution becomes brown or in that crystallization of thederivative represented by the above formula (1) of interest issignificantly inhibited, thereby making purification after the reactiondifficult.

In the present invention, the dehydrohalogenation reaction of thederivative represented by the above formula (2) or the derivativerepresented by the above formula (4) is carried out using the amidecompound represented by the above formula (5) as a base, so as toovercome the above problems. The amide compound represented by the aboveformula (5) has an extremely low basicity, and therefor it is notgenerally used as a dehydrohalogenating reagent. However, in the presentinvention, the dehydrohalogenation reaction progresses extremelyefficiently with the amide compound.

Moreover, when the above base which is conventionally used and the amidecompound represented by the above formula (5) are used in combination,there are some cases where the decomposition caused by the above basewhich is conventionally used can be prevented. However, there may stillbe problems in that the reaction solution becomes brown or in thatcrystallization of the derivative represented by the above formula (1)of interest is significantly inhibited, thereby making purificationafter the reaction difficult.

A method of producing the 5-methylene-1,3-dioxolan-4-one derivativerepresented by the above formula (1) of the present invention will beexplained. In the present invention, an amide compound represented bythe following formula (5) is used as a base:

In formula (5), each of R³, R⁴ and R⁵ independently represents ahydrogen atom, or a linear or branched alkyl group containing 1 to 4carbon atoms. R³, R⁴ and R⁵ may be identical or may be different.Examples of R⁵, R⁶ and R⁷ in the formula (5) may include a hydrogenatom, a methyl group, an ethyl group, a propyl group, an isopropylgroup, a butyl group, a tert-butyl group, and a 2-ethylhexyl group.

In terms of smooth progression of the reaction, N-methylformamide,N-ethylformamide, N,N-dimethylformamide, N,N-diethylformamide and thelike are preferable as the amide compound represented by the aboveformula (5). In terms of yield after purification, N,N-dimethylformamideis more preferable. The amide compound represented by the formula (5)may be used singly or in combination of two or more types.

In terms of yield, the use amount of the amide compound represented bythe above formula (5) is preferably-0.1 mole or more, more preferably0.5 mole or more, particularly preferably 1 mole or more, and still morepreferably 5 mole or more based on 1 mole of the derivative representedby the formula (2) or (4). In addition, in terms of disposal of thewaste liquid after the reaction, the use amount of the amide compoundrepresented by the above formula (5) is preferably 100 mole or less,more preferably 50 mole or less, and particularly preferably 30 mole orless based on 1 mole of the derivative represented by the formula (2) or(4).

In the dehydrohalogenation reaction of the present invention, an organicsolvent can be used, also. Examples of an organic solvent used hereinmay include hydrocarbon solvent such as pentane, hexane, heptane,octane, isooctane, cyclopentane, cyclohexane, benzene, and toluene;alcohol solvent such as methanol, ethanol, n-propylalcohol,isopropylalcohol, n-butylalcohol, sec-butylalcohol, tert-butylalcohol,isobutylalcohol, n-amylalcohol, isoamylalcohol, n-hexylalcohol,n-heptylalcohol, n-octylalcohol, n-nonylalcohol, n-decylalcohol,laurylalcohol, cetylalcohol, stearylalcohol, benzylalcohol,triphenylcarbinol, ethyleneglycol, 1,2-propanediol, 1,3-propanediol,1,4-butanediol, cresol, phenol, and xylenol; ether solvent such asdiethylene glycol dimethyl ether, diethylene glycol diethyl ether,triethylene glycol dimethyl ether, triethylene glycol diethyl ether,tetrahydrofuran, diethyl ether, diisopropyl ether, and methyl-tert-butylether; and chlorine-containing solvent such as carbon tetrachloride,chloroform, and methylene chloride. Such an organic solvent may be usedsingly or in combination of two or more types.

Of these, a solvent having low polarity and low mutual solubility withthe amide compound represented by the above formula (5), such aspentane, hexane, heptane, octane, isooctane, cyclopentane, cyclohexane,benzene, toluene, diethyl ether, diisopropyl ether or methyl-tert-butylether, is preferably used. When only a little derivative represented bythe above formula (1) is dissolved in the amide compound represented bythe above formula (5), the major part of the derivative represented bythe above formula (1) exists in a solvent having low polarity. So, inthis case, a product of interest can be efficiently recovered byseparating the liquid after the completion of the reaction.

In terms of reaction rate and the amount of the waste solvent, the useamount of an organic solvent is preferably 100 times by mass or less,more preferably 50 times by mass or less, and particularly preferably 20times by mass or less based on the derivative represented by the formula(2) or (4).

Alternatively, it may also be possible to carry out thedehydrohalogenation reaction without using a solvent and then to extractthe derivative represented by the above formula (1) of interest with asolvent having low polarity.

A small amount of the amide compound represented by the above formula(5) is contained in such a solvent having low polarity. However, theamide compound can be easily removed by washing with water.

Otherwise, it may also be possible to carry out the reaction withoutusing a solvent, and then to add the reaction solution to a large amountof water, so that the derivative represented by the above formula (1) ofinterest is deposited.

In general, the reaction temperature is preferably set within the rangeof −30° C. to 120° C. In terms of reaction rate, the reactiontemperature is more preferably 0° C. or higher, and particularlypreferably 10° C. or higher. Moreover, in terms of prevention of adecomposition reaction, the reaction temperature is more preferably 60°C. or lower, and particularly preferably 40° C. or lower.

Conventionally, since a dehydrohalogenation reaction causes heatgeneration, a base is added thereto while cooling. However, when theamide compound represented by the above formula (5) is used as a base inthe present invention, only a little heat is generated, and almost nodecomposition reaction progresses even at a high temperature.Accordingly, it is not necessary to cool in the present invention.

Examples of a pattern of the dehydrohalogenation reaction may include aclosed system in which the reaction is carried out under reducedpressure, under ordinary pressure or under increased pressure, using awell-closed container; and a reflux system in which the reaction iscarried out at a boiling point or lower and a volatilized raw material,product and solvent are refluxed with a condenser.

The reaction time may be determined, taking into consideration thereaction temperature or the like. Generally, the reaction time ispreferably about 1 to 48 hours.

In the present invention, when a dehydrohalogenation reaction is carriedout, a polymerization inhibitor may be added to the reaction solution,if necessary.

The polymerization inhibitor is not particularly limited, and examplesof it may include a quinone-based polymerization inhibitor such ashydroquinone, methoxyhydroquinone, benzoquinone, andp-tert-butylcatechol; an alkylphenol-based polymerization inhibitor suchas 2,6-di-tert-butylphenol, 2,4-di-tert-butylphenol,2-tert-butyl-4,6-dimethylphenol, 2,6-di-tert-butyl-4-methylphenol, and2,4,6-tri-tert-butylphenol; an amine-based polymerization inhibitor suchas alkylated diphenylamine, N,N′-diphenyl-p-phenylenediamine, andphenothiazine; and a copper dithiocarbamate-based polymerizationinhibitor such as copper dimethyldithiocarbamate, copperdiethyldithiocarbamate, and copper dibutyldithiocarbamate. Thepolymerization inhibitor may be used singly or in combination of two ormore types.

The additive amount of a polymerization inhibitor is preferably 5% orless by mass, more preferably 1% or less by mass, and particularlypreferably 0.1% or less by mass based on the mass of the derivativerepresented by the formula (2) or (4).

In the present invention, a dehydrohalogenation reaction is carried outas described above, so as to produce the derivative represented by theabove formula (1). In the present reaction, the product of interest canbe obtained at a good yield while sufficiently preventing a sidereaction. Accordingly, the derivative represented by the above formula(1) can be obtained at a high purity by a simple operation. Thepurification methods may include a known method such asrecrystallization, washing with water or an organic solvent, solventfractionation, column chromatography, distillation or short-pathdistillation.

Where R¹ differs from R² in the derivative represented by the aboveformula (1), the carbon atom at position 2 becomes an asymmetric carbon,and optical isomers exist. These optical isomers can be isolated by aknown optical resolution method such as preferential crystallizationmethod or the use of an optical resolution column. These opticallyactive substances may be either an (R)-form or a (S)-form, or may be amixture of the (R)-form and the (S)-form, and all of these substancescan be used as raw material monomers for a component resin of a coatingmaterial, an adhesive, an agglutinant, a resin for ink, a resist or thelike.

5. The First and Second Polymers of the Present Invention

Next, the first and second polymers of the present invention will beexplained. The first and second polymers of the present invention arepreferably used, for example, for a resist composition, and particularlyfor a chemically amplified resist composition.

I. The First Polymer of the Present Invention

The first polymer of the present invention is obtained by(co)polymerizing a monomer composition comprising the monomerrepresented by the above formula (1), and it comprises at least one ofconstitutional units represented by the formula (6) indicated below. Theproportion of the constitutional unit represented by the followingformula (6) in the polymer is preferably 5 mol % or more.

In formula (6), R¹ represents a bridged cyclic hydrocarbon groupcontaining 4 to 16 carbon atoms, or a linear or branched alkyl groupcontaining 1 to 6 carbon atoms which has a bridged cyclic hydrocarbongroup containing 4 to 16 carbon atoms as a substituent; R² represents ahydrogen atom, or a linear or branched alkyl group containing 1 to 6carbon atoms; or R¹ and R² represent a bridged cyclic hydrocarbon groupcontaining 4 to 16 carbon atoms together with the carbon atom to whichthey are bound.

Herein, the alkyl group and the bridged cyclic hydrocarbon group may beunsubstituted, or may have at least one substituent selected from agroup consisting of a linear or branched alkyl group containing 1 to 6carbon atoms which may be optionally substituted, a hydroxy group, acarboxy group, an acyl group containing 2 to 6 carbon atoms, an alkoxygroup containing 1 to 6 carbon atoms, and a carboxy group esterifiedwith an alcohol containing 1 to 6 carbon atoms. When the alkyl group andthe bridged cyclic hydrocarbon group have two or more substituents, thesubstituents may be of either a single type, or two or more types.

R¹ and R² in the formula (6) correspond to R¹ and R² in the formula (1),respectively. Accordingly, the R¹ and R² in the formula (6) are the sameas the R¹ and R² in the formula (1), and preferred examples of R¹ and R²in the formula (6) are also the same as the preferred examples of R¹ andR² in the formula (1).

The first polymer of the present invention may be a homopolymerconsisting of one type of the monomer represented by the above formula(1), a copolymer consisting of two or more types of the monomerrepresented by the above formula (1), or a copolymer consisting of atleast one type of the monomer represented by the above formula (1) andat least one type of monomers other than the monomer represented by theabove formula (1). When the first polymer of the present invention is acopolymer, each constitutional unit can have any given sequence.Accordingly, this polymer may be a random copolymer, an alternatingcopolymer, or a block copolymer.

In the present invention, at least one type of the monomer representedby the above formula (1) may be copolymerized with at least one type ofknown monomers other than the above monomer. Examples of a monomercapable of being copolymerized may include those that are conventionallyknown as a positive resist, a negative resist, an anti-reflection coatmaterial or an insulating film-forming material. For example, themonomer capable of being copolymerized may include a known monomer suchas an acrylic acid derivative and a methacrylic acid derivative, whichhave a dry etching resistance-improving group or a soluble groupinvolving acid dissociation, a carboxylic acid (including a derivativethereof) having an ethylene double bond causing alkali solubility, andknown monomers used in the production of an acrylic resin.

Examples of an acrylic acid derivative may include acryl ester in whichthe hydroxyl group of the carboxy group is protected with anacid-dissociating substituent, such as tert-butyl acrylate,tetrahydropyranyl acrylate, tetrahydrofuranyl acrylate,1-methylcyclohexyl acrylate, 1-methyladamantyl acrylate, ethoxyethylacrylate, ethoxypropyl acrylate, and the ester of acrylic acid and2-hydroxy-3-pinanone; or acryl ester in which the hydroxyl group of thecarboxy group is protected with an non-acid-dissociating substituent,such as adamantyl acrylate, cyclohexyl acrylate, naphthyl acrylate,benzyl acrylate, 3-oxocyclohexyl acrylate, bicyclo[2.2.1]heptylacrylate, tricyclodecanyl acrylate, the ester of acrylic acid andterpineol, and the ester of acrylic acid and 3-bromoacetone.

Examples of a methacrylic acid derivative may include methacrylic acidderivatives corresponding to the above listed acrylic acid derivatives.

In addition, examples of a carboxylic acid having an ethylene doublebond may include acrylic acid; methacrylic acid; maleic acid; fumaricacid; norbornene or a norbornene derivative having an alkyl group, analkyloxy group, a hydroxyl group, a hydroxyalkyl group, a carboxy group,an alkyloxycarbonyl group, or the like as a substituent; a vinyl etherderivative such as ethyl vinyl ether, cyclohexyl vinyl ether, andhydroxyethyl vinyl ether; a styrene derivative such as styrene,p-hydroxystyrene, p-methoxystyrene, and p-tert-butoxystyrene; and maleicanhydride.

Examples of a known monomer used in the production of an acrylic resinmay include acrylic acid; methacrylic acid; or an acrylic acidderivative or an methacrylic acid derivative in which the hydrogen atomof these carboxylic acids is substituted with a group such as a methylgroup, an ethyl group, a n-propyl group, an isopropyl group, a n-butylgroup, a tert-butyl group, a n-hexyl group, an octyl group, a2-ethylhexyl group, a lauryl group, a 2-hydroxyethyl group, a2-hydroxypropyl group, a cyclopentyl group, a cyclohexyl group, a2-hydroxyethyl group, a norbornyl group, a tricyclodecanyl group, anadamantyl group, a 2-methyl-2-adamantyl group, a tetrahydropyranylgroup, a tetrahydrofuranyl group, or the like.

The first polymer of the present invention is preferably used as amaterial for a resist composition, and particularly as a material for achemically amplified resist composition. Hereinafter, a case where thefirst polymer of the present invention is a resin used for a chemicallyamplified resist composition will be explained.

The resin for a chemically amplified resist composition is required tohave both a property for becoming soluble in an alkaline aqueoussolution by an acid so as to realize high sensitivity and a structurehaving high carbon density so as to realize high dry etching resistance.The first polymer of the present invention is excellent in solubility inan organic solvent and heat resistance, and has little line edgeroughness. When a structure having a property for becoming soluble in analkaline aqueous solution by the action of an acid, or a structurehaving high dry etching resistance is introduced into such a polymer, anexcellent resin for a chemically amplified resist composition can beobtained.

Examples of the structure having a functional group that is easilyeliminated by the action of an acid may include a structure in which ahydroxy group or a carboxy group is protected with an acyl group such asan acetyl group, a tert-butyl group, a tetrahydropyranyl group, a2-methyl-2-adamantyl group or other groups is.

Examples of the structure having high carbon density may include anisobornyl group, an adamantly group, a 2-methyl-adamantyl group, a3-hydroxy-1-adamantyl group, a tricyclodecanyl group, anddicyclopentadienyl group.

In order to introduce the structure having a functional group that iseasily eliminated by the action of an acid or the structure having highcarbon density into the polymer, the monomer of the present inventionmay be copolymerized with a monomer having such a structure.

As a monomer having such a structure, for example, the one that is knownas a raw material monomer for a resin for a chemically amplified resistcomposition can be used. A raw material monomer used for the polymer ofthe present invention is arbitrarily selected depending on light sourceused in lithography.

For example, when a KrF excimer laser or an electron beam is used as alight source, considering its high etching resistance, a polymerobtained by copolymerizing the monomer of the present invention withp-hydroxystyrene or a derivative thereof is preferably used. In thiscase, the proportion of the constitutional unit derived from the monomerof the present invention in the polymer is preferably 5% or more and ispreferably 60% or less.

When an ArF excimer laser is used as a light source, a polymer obtainedby copolymerizing the monomer of the present invention with a monomerhaving a cyclic hydrocarbon group is preferably used. Copolymerizationwith a monomer having a cyclic hydrocarbon group enables high etchingresistance.

Among them, a polymer obtained by copolymerizing the monomer of thepresent invention, a monomer having a cyclic hydrocarbon group, amonomer having a hydrophilic functional group and/or a monomer having alactone structure is preferable.

It is known that an acrylic copolymer obtained by copolymerizing amonomer having a cyclic hydrocarbon group and a monomer having ahydrophilic functional group, or an acrylic copolymer obtained bycopolymerizing a monomer having a cyclic hydrocarbon group and a monomerhaving a lactone structure, is preferable as a resin for the ArF excimerlaser lithography. Introduction of the monomer unit of the presentinvention into these polymers enables improvement of solubility in anorganic solvent and heat resistance without impairing the resistperformance such as high sensitivity, high resolution or high dryetching resistance, thereby providing an excellent resist pattern withonly a little line edge roughness.

A monomer unit having a cyclic hydrocarbon group imparts high dryetching resistance to a polymer comprising the same. In particular, amonomer unit having a protecting group that is eliminated by an acid (acyclic hydrocarbon group may also be a protecting group by itself)imparts also high sensitivity to the polymer comprising the same inphotolithography using an ArF excimer laser with a wavelength of 193 nm.The monomer units having a cyclic hydrocarbon group may be of either asingle type, or two or more types, if necessary.

Preferred examples of the monomer unit having a cyclic hydrocarbon groupmay include cyclohexyl (meth)acrylate, isobornyl (meth)acrylate,adamantyl (meth)acrylate, tricyclodecanyl (meth)acrylate, dicyclopentyl(meth)acrylate, and derivatives having a substituent such as an alkylgroup, a hydroxy group or a carboxy group on the cyclic hydrocarbongroup of these monomers.

Specific examples of such a monomer unit may include 1-isobornyl(meth)acrylate, 2-(meth)acryloyloxy-2-methyladamantane,2-(meth)acryloyloxy-2-ethyladamantane,1-(meth)acryloyloxy-3-hydroxyadamantane, cyclohexyl (meth)acrylate,adamantyl (meth)acrylate, tricyclodecanyl (meth)acrylate, anddicyclopentyl (meth)acrylate.

A monomer unit having a hydrophilic functional group imparts adhesion toa substrate to a polymer comprising the same. In particular, a monomerunit having a protecting group that is eliminated by an acid impartsalso high sensitivity to the polymer comprising the same inphotolithography using an ArF excimer laser with a wavelength of 193 nm.Examples of a hydrophilic functional group may include a terminalhydroxy group, an alkyl-substituted ether group, a 6-valerolactonylgroup, and a γ-butyrolactonyl group. It should be noted that some of theabove listed hydrophilic functional groups are generally included inhydrophobic groups. However, since even such functional groups havehydrophilicity that is needed in the present invention, they are hereindefined as a hydrophilic functional group. The monomer units having ahydrophilic functional group may be of either a single type, or two ormore types, if necessary.

Preferred examples of the monomer unit having a hydrophilic functionalgroup may include (meth)acrylate having a terminal hydroxy group,(meth)acrylate having an alkyl-substituted ether group, (meth)acrylatehaving a δ-valerolactonyl group, (meth)acrylate having aγ-butyrolactonyl group, and derivatives having a substituent such as analkyl group, a hydroxy group or a carboxy group on the hydrophilicfunctional group of these monomers.

Specific examples of such a monomer unit may include 2-hydroxyethyl(meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl(meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl(meth)acrylate, β-(meth)acryloyloxy-β-methyl-δ-valerolactone,β-(meth)acryloyloxy-γbutyrolactone,β-(meth)acryloyloxy-β-methyl-γ-butyrolactone,α-(meth)acryloyloxy-γ-butyrolactone,2-(1-(meth)acryloyloxy)ethyl-4-butanolide, pantolactone (meth)acrylate,and a mixture of8-methacryloyloxy-3-oxatricyclo[5.2.1.0^(2,6)]decan-2-one and9-methacryloyloxy-3-oxatricyclo[5.2.1.0^(2,6)]decan-2-one.

A monomer unit having a lactone structure imparts high dry etchingresistance and adhesion to a substrate to a polymer comprising the same.The monomer units having a lactone structure may be of either a singletype, or two or more types, if necessary.

Preferred examples of the monomer unit having a lactone structure mayinclude 4-8 membered α-methylenelactone, and derivatives having asubstituent such as an alkyl group, a hydroxy group or a carboxy groupon a carbon of the lactone ring of these monomers. In particular,α-methylene-γ-butyrolactone, and the derivative having a substituentsuch as an alkyl group, a hydroxy group or a carboxy group on the carbonof the γ position are preferable.

Specific examples of such a monomer unit may include2-methylene-4-butanolide, 4-methyl-2-methylene-4-butanolide,4-ethyl-2-methylene-4-butanolide, and4,4-dimethyl-2-methylene-4-butanolide.

Among them, as a resin for a chemically amplified resist composition, apolymer comprising at least one of constitutional units represented bythe formula (6) and at least one of constitutional units represented bythe formula (8), (9) or (10) is preferable. Such a polymer comprising atleast one of constitutional units represented by the formula (6) and atleast one of constitutional units represented by the formula (8), (9) or(10) will be described in the section 11. The second polymer of thepresent invention.

The mass-average molecular weight of the first polymer of the presentinvention is not particularly limited. However, when the polymer is usedas a resin for a resist composition, the mass-average molecular weightof the first polymer of the present invention is preferably 1,000 ormore because the dry etching resistance is improved at the above range,thereby bettering the form of the resist. In addition, it is preferably100,000 or less because the solubility in a resist solution is improvedat the above range, thereby bettering the resolution.

II. The Second Polymer of the Present Invention

The second polymer of the present invention comprises at least one ofconstitutional units represented by the following formula (7) and atleast one of constitutional units represented by the following formula(8), (9) or (10):

In formula (7), each of R⁶ and R⁷ independently represents a hydrogenatom, a linear or branched alkyl group containing 1 to 6 carbon atoms, acyclic hydrocarbon group containing 4 to 16 carbon atoms, or a linear orbranched alkyl group containing 1 to 6 carbon atoms which has a cyclichydrocarbon group containing 4 to 16 carbon atoms as a substituent; orR⁶ and R⁷ represent a cyclic hydrocarbon group containing 4 to 16 carbonatoms together with the carbon atom to which they are bound. R⁶ and R⁷may be identical or may be different.

Herein, the alkyl group and the cyclic hydrocarbon group may beunsubstituted, or may have at least one substituent selected from agroup consisting of a linear or branched alkyl group containing 1 to 6carbon atoms which may be optionally substituted, a hydroxy group, acarboxy group, an acyl group containing 2 to 6 carbon-atoms, an alkoxygroup containing 1 to 6 carbon atoms, and a carboxy group esterifiedwith an alcohol containing 1 to 6 carbon atoms. When the alkyl group andthe cyclic hydrocarbon group have two or more substituents, thesubstituents may be of either a single type, or two or more types.

In formula (8), R⁸ represents a hydrogen atom or a methyl group, and R⁹represents a linear or branched alkyl group containing 1 to 6 carbonatoms, a cyclic hydrocarbon group containing 4 to 8 carbon atoms, or abridged cyclic hydrocarbon group containing 4 to 16 carbon atoms.

Herein, the alkyl group, the cyclic hydrocarbon group and the bridgedcyclic hydrocarbon group may be unsubstituted, or may have at least onesubstituent selected from a group consisting of a linear or branchedalkyl group containing 1 to 6 carbon atoms which may be optionallysubstituted, a hydroxy group, a carboxy group, and a carboxy groupesterified with an alcohol containing 1 to 6 carbon atoms. When thealkyl group, the cyclic hydrocarbon group and the bridged cyclichydrocarbon group have two or more substituents, the substituents may beof either a single type, or two or more types.

In formula (9), R¹⁰ represents a hydrogen atom or a methyl group, andR¹¹ represents a hydrogen atom, a hydrophilic functional group, a linearor branched alkyl group containing 1 to 6 carbon atoms which has ahydrophilic functional group, a cyclic hydrocarbon group containing 4 to8 carbon atoms which has a hydrophilic functional group, or a bridgedcyclic hydrocarbon group containing 4 to 16 carbon atoms which has ahydrophilic functional group.

Herein, the alkyl group, the cyclic hydrocarbon group, the bridgedcyclic hydrocarbon group and the hydrophilic functional group may beunsubstituted, or may have at least one substituent selected from agroup consisting of a linear or branched alkyl group containing 1 to 6carbon atoms which may be optionally substituted, a hydroxy group, acarboxy group, and a carboxy group esterified with an alcohol containing1 to 6 carbon atoms. When the alkyl group, the cyclic hydrocarbon group,the bridged cyclic hydrocarbon group and the hydrophilic functionalgroup have two or more substituents, the substituents may be of either asingle type, or two or more types.

Examples of a hydrophilic functional group in the formula (9) mayinclude groups with high polarity, such as a hydroxyl group, a carboxygroup or an amino group; linear or branched alkyl groups having astructure such as ketone, acid anhydride, ester, ether, lactone, imideor amide; and cyclic compounds. Compounds having a hydrophilicfunctional group may include monocyclic saturated hydrocarbon groupscontaining 4 to 8 carbon atoms or a bridged cyclic hydrocarbon groupscontaining 4 to 16 carbon atoms, a portion of the skeleton of which issubstituted with a structure such as ketone, acid anhydride, ester,ether, lactone, imide or amide. Some of the above listed hydrophilicfunctional groups are generally included in hydrophobic groups. However,since even such functional groups have hydrophilicity that is needed fora resist composition of the present invention, they are herein definedas a hydrophilic functional group.

In formula (10), each of R¹² and R¹³ independently represents a hydrogenatom, a methyl group or an ethyl group, and q represents an integer of 1to 4. R¹² and R¹³ may be identical or may be different.

Herein, C_(q)H_(2q) represents a methylene chain containing 1 to 4carbon atoms [—(CH₂)_(q)— (wherein q represents an integer of 1 to 4)].

In the second polymer of the present invention, the constitutional units(7), (8), (9) and (10) are not necessarily of the same type, but two ormore types may be mixed therein as long as they are represented by theabove general formulas. Moreover, in this polymer, each constitutionalunit can have any given sequence. Accordingly, this polymer may be arandom copolymer, an alternating copolymer, or a block copolymer.

Examples of a substituent on the linear or branched alkyl groupcontaining 1 to 6 carbon atoms that is the substituent on the alkylgroup, the cyclic hydrocarbon group, the bridged cyclic hydrocarbongroup and the hydrophilic functional group, may include a hydroxy group,a carboxy group, an acyl group containing 1 to 6 carbon atoms, and anamino group. The number of substituents may be either one, or two ormore. When the above group has two or more substituents, thesubstituents may be of either a single type, or two or more types.

Examples of R⁶ and R⁷ in the above formula (7) may include a hydrogenatom, a methyl group, an ethyl group, a propyl group, an isopropylgroup, a butyl group, a tert-butyl group, a cyclopentyl group, acyclohexyl group, a cycloheptyl group, a 2-norbornyl group, a1-adamantyl group, a 1-adamantanemethyl group, a 1-adamantaneethylgroup, a 2-adamantyl group, a 2-adamantanemethyl group, a2-adamantaneethyl group and a 2-adamantanonyl group. Moreover, R⁶ and R⁷may include a structure wherein these groups are substituted with atleast one substituent selected from a group consisting of a linear orbranched alkyl group containing 1 to 6 carbon atoms which may beoptionally substituted (e.g., a hydroxy group, a carboxy group, acarboxy group esterified with an alcohol containing 1 to 6 carbon atoms,an acyl group containing 1 to 6 carbon atoms, an amino group, and thelike), a hydroxy group, a carboxy group, an acyl group containing 2 to 6carbon atoms, an alkoxy group containing 1 to 6 carbon atoms, and acarboxy group esterified with an alcohol containing 1 to 6 carbon atoms,or the like. The number of substituents may be either one, or two ormore. When the above group has two or more substituents, thesubstituents may be of either a single type, or two or more types.

Moreover, R⁶ and R⁷ in the above formula (7) may form a cyclichydrocarbon structure containing 4 to 16 carbon atoms, together with thecarbon atom to which they are bound. Examples of such a cyclichydrocarbon structure may include an adamantylidene group, anorbornylidene group, and a cyclohexylidene group. Furthermore, examplesof such a cyclic hydrocarbon structure may also include those whereinthe cyclic hydrocarbon structure containing 4 to 16 carbon atoms issubstituted with at least one substituent selected from a groupconsisting of a linear or branched alkyl group containing 1 to 6 carbonatoms which may be optionally substituted (e.g., a hydroxy group, acarboxy group, a carboxy group esterified with an alcohol containing 1to 6 carbon atoms, an acyl group containing 1 to 6 carbon atoms, anamino group, and the like), a hydroxy group, a carboxy group, an acylgroup containing 2 to 6 carbon atoms, an alkoxy group containing 1 to 6carbon atoms, and a carboxy group esterified with an alcohol containing1 to 6 carbon atoms, or the like. The number of substituents may beeither one, or two or more. When the structure has two or moresubstituents, the substituents may be of either a single type, or two ormore types.

As the constitutional unit represented by the above formula (7), aconstitutional unit wherein R⁶ represents a hydrogen atom, a methylgroup or an ethyl group and R⁷ represents a cyclopentyl group, acyclohexyl group or a cycloheptyl group, and a constitutional unitwherein R⁶ and R⁷ form a cyclic hydrocarbon group containing 5 to 8carbon atoms together with the carbon atom to which they are bound, arepreferable. Among them, the constitutional unit represented by the aboveformula (6) is particularly preferable.

The constitutional unit represented by the above formula (8) is obtainedby copolymerizing a monomer such as cyclohexyl (meth)acrylate,1-isobornyl (meth)acrylate, adamantyl (meth)acrylate, tricyclodecanyl(meth)acrylate, dicyclopentyl (meth)acrylate,2-(meth)acryloyloxy-2-methyladamantane,2-(meth)acryloyloxy-2-ethyladamantane, or derivatives having asubstituent such as an alkyl group, a hydroxy group or a carboxy groupon the cyclic hydrocarbon group of these monomers.

In terms of sensitivity and resolution when the polymer is used as aresist composition material, a constitutional unit derived from2-(meth)acryloyloxy-2-methyladamantane, and a constitutional unitderived from 2-(meth)acryloyloxy-2-ethyladamantane are preferable, asthe constitutional unit represented by the above formula (8).

The constitutional unit represented by the above formula (9) is obtainedby copolymerizing a monomer having a hydrophilic functional group, suchas (meth)acrylate having a terminal hydroxy group, (meth)acrylate havingan alkyl-substituted ether group, (meth)acrylate having aδ-valerolactonyl group, or (meth)acrylate having a γ-butyrolactonylgroup; derivatives having a substituent such as an alkyl group, ahydroxy group or a carboxy group on the hydrophilic functional group ofthese monomers; or a monomer having a hydrophilic functional group suchas a hydroxy group or a carboxy group on the cyclic hydrocarbon group ofa monomer such as cyclohexyl (meth)acrylate, 1-isobornyl (meth)acrylate,adamantyl (meth)acrylate, tricyclodecanyl (meth)acrylate, dicyclopentyl(meth)acrylate, 2-(meth)acryloyloxy-2-methyladamantane or2-(meth)acryloyloxy-2-ethyladamantane. Specific examples of such amonomer may include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl(meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-methoxyethyl(meth)acrylate, 2-ethoxyethyl (meth)acrylate,1-methacryloyloxy-3-hydroxyadamantane,β-(meth)acryloyloxy-β-methyl-β-valerolactone,β-(meth)acryloyloxy-γ-butyrolactone,β-(meth)acryloyloxy-β-methyl-γ-butyrolactone,α-(meth)acryloyloxy-γ-butyrolactone,2-(1-(meth)acryloyloxy)ethyl-4-butanolide, pantolactone (meth)acrylate,8-methacryloyloxy-3-oxatricyclo[5.2.1.0^(2,6)]decan-2-one, and9-methacryloyloxy-3-oxatricyclo[5.2.1.0^(2,6)]decan-2-one.

In terms of adhesion to a substrate when the polymer is used as a resistcomposition material, a constitutional unit derived from1-methacryloyloxy-3-hydroxyadamantane, a constitutional unit derivedfrom 8-methacryloyloxy-3-oxatricyclo[5.2.1.0^(2,6)]decan-2-one, and aconstitutional unit derived from9-methacryloyloxy-3-oxatricyclo[5.2.1.0²-6]decan-2-one are preferable,as the constitutional unit represented by the above formula (9).

The constitutional unit represented by the above formula (10) isobtained by copolymerizing a monomer such as 4-8 memberedα-methylenelactone, or derivatives having a substituent such as an alkylgroup, a hydroxy group or a carboxy group on a carbon of the lactonering of these monomers.

In terms of sensitivity and resolution when the polymer is used as aresist composition material, a constitutional unit derived fromα-methylene-γ-butyrolactone, and a constitutional unit derived from itsderivatives having a substituent such as a methyl group or an ethylgroup on the carbon of the γ position, for example,α-methyleney-butyrolactone, α-methylene-γ-methyl-γ-butyrolactone,α-methylene-γ-ethyl-γ-butyrolactone, and4,4-dimethyl-2-methylene-4-butanolide, are preferable, as theconstitutional unit represented by the above formula (10).

In order to improve solubility of the polymer in an organic solvent andheat resistance and to reduce line edge roughness, the proportion of theconstitutional unit represented by the above formula (7) is preferably 5mol % or more in the polymer. Moreover, in order not to reducesensitivity and resolution, the proportion of the constitutional unitrepresented by the above formula (7) is preferably 50 mol % or less inthe polymer.

In order to improve sensitivity and resolution, the proportion of theconstitutional unit represented by the above formula (8) is preferably30 mol % or more in the polymer. Moreover, in order not to reducesolubility of the polymer in an organic solvent, the proportion of theconstitutional unit represented by the above formula (8) is preferably70 mol % or less in the polymer.

In order not to reduce dry etching resistance, the proportion of theconstitutional unit represented by the above formula (9) is preferably70 mol % or less in the polymer.

In order not to reduce sensitivity and resolution, the proportion of theconstitutional unit represented by the above formula (10) is preferably60 mol % or less in the polymer.

The second polymer of the present invention is preferably used as amaterial for a resist composition, and particularly as a material for achemically amplified resist composition. The second polymer of thepresent invention is particularly excellent in sensitivity, resolution,and the like.

Moreover, the second polymer of the present invention may comprise atleast one type of constitutional units derived from known monomers otherthan the constitutional units represented by the above formulas (7) to(10). Specific examples of a monomer capable of being copolymerized or aconstitutional unit may be the same as those described in the firstpolymer of the present invention.

The mass-average molecular weight of the second polymer of the presentinvention is not particularly limited. However, when the polymer is usedas a resin for a resist composition, the mass-average molecular weightof the second polymer of the present invention is preferably 1,000 ormore because the dry etching resistance is improved at the above range,thereby bettering the form of the resist. In addition, it is preferably100,000 or less because the solubility in a resist solution is improvedat the above range, thereby bettering the resolution.

5. The Third, Fourth and Fifth Polymers of the Present Invention

Next, the third, fourth and fifth polymers of the present invention willbe explained. The third, fourth and fifth polymers of the presentinvention are preferably used, for example, for a resist composition,and particularly for a chemically amplified resist composition.

I. The Third Polymer of the Present Invention

The third polymer of the present invention comprises at least one ofconstitutional units represented by the formula (11) indicated below.The proportion of the constitutional unit represented by the followingformula (11) in the polymer is preferably 5 mol % or more.

In formula (11), W¹ represents a direct bond or a methylene chaincontaining 1 to 6 carbon atoms [—(CH₂)_(k)— (wherein k represents aninteger of 0 to 6)], W² represents a direct bond or a methylene chaincontaining 1 to 3 carbon atoms [—(CH₂)₁— (wherein I represents aninteger of 0 to 3)], W³ represents a methylene chain containing 1 to 3carbon atoms [—(CH₂)_(m)— (wherein m represents an integer of 1 to 3)],R¹⁴ represents a hydrogen atom or a methyl group, R¹⁵ represents abridged cyclic hydrocarbon group containing 4 to 16 carbon atoms, or alinear or branched alkyl group containing 1 to 6 carbon atoms which hasa bridged cyclic hydrocarbon group containing 4 to 16 carbon atoms as asubstituent, R¹⁶ represents a hydrogen atom, or a linear or branchedalkyl group containing 1 to 6 carbon atoms; or R¹⁵ and R¹⁶ represent abridged cyclic hydrocarbon group containing 4 to 16 carbon atomstogether with the carbon atom to which they are bound.

Herein, the methylene chain containing 1 to 6 carbon atoms may have, asa substituent, an alkyl group containing 1 to 3 carbon atoms which maybe optionally substituted, and may optionally have at least one etherbond therein. The methylene chain containing 1 to 3 carbon atoms mayhave a carbonyl group therein. Further, the alkyl group and the bridgedcyclic hydrocarbon group may be unsubstituted, or may have at least onesubstituent selected from a group consisting of a linear or branchedalkyl group containing 1 to 6 carbon atoms which may be optionallysubstituted, a hydroxy group, a carboxy group, an acyl group containing2 to 6 carbon atoms, an alkoxy group containing 1 to 6 carbon atoms, anda carboxy group esterified with an alcohol containing 1 to 6 carbonatoms. When the alkyl group and the bridged cyclic hydrocarbon grouphave two or more substituents, the substituents may be of either asingle type, or two or more types.

Examples of a substituent on the linear or branched alkyl groupcontaining 1 to 6 carbon atoms that is the substituent on the alkylgroup and the bridged cyclic hydrocarbon group may include a hydroxygroup, a carboxy group, an acyl group containing 1 to 6 carbon atoms,and an amino group. The number of substituents may be either one, or twoor more. When the above group has two or more substituents, thesubstituents may be of either a single type, or two or more types.

Herein, the bridged cyclic hydrocarbon group is a group having astructure represented by the following formula (15) or (16) includingadamantane and norbornane as typical examples:

wherein each of A¹ and B¹ represents a linear or branched alkylenegroup, and A¹ and B¹ may be identical or may be different; or

wherein each of A², B² and L represents a linear or branched alkylenegroup, and A², B² and L may be identical or may be different.

Examples of W¹ in the above formula (11) may include a direct bond(which means that the oxygen atom and the carbon atom that are adjacentto W¹ are directly bound to each other), CH₂, CH₂CH₂, CH₂CH₂CH₂,CH(CH₃)CH₂, CH₂O, CH₂CH₂O, CH₂CH(CH₃)O, CH(CH₃)CH₂O, CH₂CH₂OCH₂CH₂O,CH₂CH(CH₃)OCH₂CH(CH₃)O, and CH(CH₃)CH₂OCH(CH₃)CH₂O.

Of these, in terms of storage stability of the polymer, a direct bond,CH₂, CH₂CH₂O and CH₂CH(CH₃)O are preferable as W¹.

Examples of W² in the above formula (11) may include a direct bond(which means that the oxygen atom and the carbon atom that are adjacentto W² are directly bound to each other), CH₂, C(O), CH₂CH₂, CH₂C(O),CH₂CH₂CH₂, and CH₂C(O)CH₂.

Of these, in terms of storage stability of the polymer, a direct bond,CH₂, C(O) and CH₂C(O) are preferable as W².

Examples of W³ in the above formula (11) may include CH₂, C(O), CH₂CH₂,CH₂C(O), CH₂CH₂CH₂, and CH₂C(O)CH₂.

Of these, in terms of storage stability of the polymer, CH₂, C(O) andCH₂C(O) are preferable as W³.

Examples of R¹⁵ in the above formula (11) may include bridged cyclichydrocarbon groups such as a 2-norbornyl group, a 1-adamantyl group, a1-adamantanemethyl group, a 1-adamantaneethyl group, a 2-adamantylgroup, a 2-adamantanemethyl group, a 2-adamantaneethyl group or a2-adamantanonyl group. Moreover, examples of R¹⁵ may include a structurewherein these groups are substituted with at least one substituentselected from a group consisting of a linear or branched alkyl groupcontaining 1 to 6 carbon atoms which may be optionally substituted(e.g., a hydroxy group, a carboxy group, a carboxy group esterified withan alcohol containing 1 to 6 carbon atoms, an acyl group containing 1 to6 carbon atoms, an amino group, and the like), a hydroxy group, acarboxy group, an acyl group containing 2 to 6 carbon atoms, an alkoxygroup containing 1 to 6 carbon atoms, and a carboxy group esterifiedwith an alcohol containing 1 to 6 carbon atoms, or the like. The numberof substituents may be either one, or two or more. When the above grouphas two or more substituents, the substituents may be of either a singletype, or two or more types.

Of these, in terms of having excellent dry etching resistance when thepolymer is used for a resist composition, a 2-norbornyl group, a1-adamantyl group, a 1-adamantanemethyl group, a 1-adamantaneethylgroup, a 2-adamantyl group, a 2-adamantanemethyl group and a2-adamantaneethyl group are preferable as R¹⁵. In terms of the lighttransparency and heat stability such as Tg of the (co)polymer to beobtained, a 1-adamantyl group and a 2-norbornyl group are morepreferable as R¹⁵.

Examples of R¹⁶ in the above formula (11) may include a hydrogen atom, amethyl group, an ethyl group, a propyl group, an isopropyl group, abutyl group and a tert-butyl group. Moreover, examples of R¹⁶ mayinclude a structure wherein these groups are substituted with at leastone substituent selected from a group consisting of a linear or branchedalkyl group containing 1 to 6 carbon atoms which may be optionallysubstituted (e.g., a hydroxy group, a carboxy group, a carboxy groupesterified with an alcohol containing 1 to 6 carbon atoms, an acyl groupcontaining 1 to 6 carbon atoms, an amino group, and the like), a hydroxygroup, a carboxy group, an acyl group containing 2 to 6 carbon atoms, analkoxy group containing 1 to 6 carbon atoms, and a carboxy groupesterified with an alcohol containing 1 to 6 carbon atoms, or the like.The number of substituents may be either one, or two or more. When theabove group has two or more substituents, the substituents may be ofeither a single type, or two or more types.

Of these, a methyl group and an ethyl group are preferable as R⁶, interms of having excellent coatability when the polymer is used for aresist composition.

Further, R¹⁵ and R¹⁶ in the above formula (11) may form a bridged cyclichydrocarbon structure containing 4 to 16 carbon atoms, together with thecarbon atom to which they are bound. Examples of such a bridged cyclichydrocarbon structure may include an adamantylidene group and anorbornylidene group. Furthermore, examples of such a bridged cyclichydrocarbon structure may also include those wherein the bridged cyclichydrocarbon structure containing 4 to 16 carbon atoms is substitutedwith at least one substituent selected from a group consisting of alinear or branched alkyl group containing 1 to 6 carbon atoms which maybe optionally substituted (e.g., a hydroxy group, a carboxy group, acarboxy group esterified with an alcohol containing 1 to 6 carbon atoms,an acyl group containing 1 to 6 carbon atoms, an amino group, and thelike), a hydroxy group, a carboxy group, an acyl group containing 2 to 6carbon atoms, an alkoxy group containing 1 to 6 carbon atoms, and acarboxy group esterified with an alcohol containing 1 to 6 carbon atoms,or the like. The number of substituents may be either one, or two ormore. When the above structure has two or more substituents, thesubstituents may be of either a single type, or two or more types.

As stated above, in the above compounds, an alkyl group and/or a bridgedcyclic hydrocarbon group may be substituted with a linear or branchedalkyl group containing 1 to 6 carbon atoms which may be optionallysubstituted (e.g., a hydroxy group, a carboxy group, a carboxy groupesterified with an alcohol containing 1 to 6 carbon atoms, an acyl groupcontaining 1 to 6 carbon atoms, an amino group, and the like), a hydroxygroup, a carboxy group, an acyl group containing 2 to 6 carbon atoms, analkoxy group containing 1 to 6 carbon atoms, a carboxy group esterifiedwith an alcohol containing 1 to 6 carbon atoms, or the like. The numberof substituents may be either one, or two or more. When the abovecompound has two or more substituents, the substituents may be of eithera single type, or two or more types.

Of these, a linear or branched alkyl group containing 1 to 6 carbonatoms which may be optionally substituted, a hydroxy group, a carboxygroup, an acyl group containing 2 to 6 carbon atoms, an alkoxy groupcontaining 1 to 6 carbon atoms, and a carboxy group esterified with analcohol containing 1 to 6 carbon atoms are preferable as a substituent,in terms of having excellent light transparency when the polymer is usedfor a resist composition. Moreover, in terms of having excellent dryetching resistance when the polymer is used for a resist composition, amethyl group and an ethyl group are more preferable as a substituent.And, in terms of having excellent adhesion of the polymer to a substratewhen the polymer is used for a resist composition, a hydroxyl group, ahydroxymethyl group, and a hydroxyethyl group are more preferable as asubstituent.

The third polymer of the present invention comprising at least one ofconstitutional units represented by the above formula (11) is obtainedby (co)polymerizing a monomer composition comprising a monomerrepresented by the following formula (I):

W¹, W², W³, R¹⁴, R¹⁵ and R¹⁶ in the formula (1) correspond to W¹, W²,W³, R¹⁴, R¹⁵ and R¹⁶ in the formula (11), respectively.

Examples of the monomer represented by the above formula (1) may includemonomers represented by the formulas (I-1) to (I-45) indicated below. Inthe formulas (I-1) to (I-45), R¹⁴ is the same as in the above formula(11), and it represents a hydrogen atom or a methyl group.

Among the monomers represented by the above formula (1), thoserepresented by the above formulas (I-37) to (I-45) are preferable interms of storage stability of the polymer.

The monomer represented by the above formula (I) can be produced, forexample, by following the process (Scheme 1) indicated below.

A raw material ketone such as 2-adamantanone, 1-adamantyl methyl ketone,norcampher and derivatives thereof are commercially available, or theycan be synthesized by a known production method, and all of them can beused.

A method of synthesizing a cyclic acetal from a ketone and a diol or ahydroxycarboxylic acid under acid conditions is widely known. A lowpolar solvent such as toluene, cyclohexane or hexane is preferably usedas a reaction solvent. Moreover, in advance of the reaction, watercontained in the reaction system is preferably removed so as to increaseyield.

The esterification reaction of the alcohol can be carried out undercommon esterification conditions. Examples of a reactant may include a(meth)acrylic halide, a (meth)acrylic anhydride, a (meth)acrylic esterand (meth)acrylic acid. Moreover, a catalyst used in esterification,such as an acid, a base, a Lewis acid or an enzyme, may be used.

In some cases, the product of this reaction may comprise severalconstitutional isomers, geometric isomers or optical isomers. In thepresent invention, both a mixture consisting of such isomers and aproduct containing an intermediate can be used. If necessary, theobtained reaction product may be purified by a known method such asdistillation, short-path distillation, recrystallization or columnchromatography.

The third polymer of the present invention may be a homopolymerconsisting of one type of the monomer represented by the above formula(I), a copolymer consisting of two or more types of the monomerrepresented by the above formula (I), or a copolymer consisting of atleast one type of the monomer represented by the above formula (I) andat least one type of monomers other than the monomer represented by theabove formula (I). When the third polymer of the present invention is acopolymer, each constitutional unit can have any given sequence.Accordingly, this polymer may be a random copolymer, an alternatingcopolymer, or a block copolymer.

In the present invention, at least one type of the monomer representedby the above formula (I) may be copolymerized with at least one type ofknown monomers other than the above monomer. Examples of a monomercapable of being copolymerized may include those that are conventionallyknown as a positive resist, a negative resist, an anti-reflection coatmaterial or an insulating film-forming material. For example, themonomer capable of being copolymerized may include a known monomer suchas an acrylic acid derivative and a methacrylic acid derivative, whichhave a dry etching resistance-improving group or a soluble groupinvolving acid dissociation, a carboxylic acid (including a derivativethereof) having an ethylene double bond causing alkali solubility, andknown monomers used in the production of an acrylic resin. Specificexamples of a monomer capable of being copolymerized may be the same asthose described in the first polymer of the present invention.

The third polymer of the present invention is preferably used as amaterial for a resist composition, and particularly as a material for achemically amplified resist composition. Hereinafter, a case where thethird polymer of the present invention is a resin used for a chemicallyamplified resist composition will be explained.

As described in the first polymer of the present invention, the resinfor a chemically amplified resist composition is required to have both aproperty for becoming soluble in an alkaline aqueous solution by an acidso as to realize high sensitivity and a structure having high carbondensity so as to realize high dry etching resistance. The third polymerof the present invention is excellent in solubility in an organicsolvent and heat resistance, and has little line edge roughness. When astructure having a property for becoming soluble in an alkaline aqueoussolution by the action of an acid, or a structure having high dryetching resistance is introduced into such a polymer, an excellent resinfor a chemically amplified resist composition can be obtained.

Examples of the structure having a functional group that is easilyeliminated by the action of an acid and the structure having high carbondensity may be the same as those described in the first polymer of thepresent invention.

In order to introduce the structure having a functional group that iseasily eliminated by the action of an acid or the structure having highcarbon density into the polymer, the monomer of the present inventionmay be copolymerized with a monomer having such a structure.

As a monomer having such a structure, for example, the one that is knownas a raw material monomer for a resin for a chemically amplified resistcomposition can be used. A raw material monomer used for the polymer ofthe present invention is arbitrarily selected depending on light sourceused in lithography.

For example, when a KrF excimer laser or an electron beam is used as alight source, considering its high etching resistance, a polymerobtained by copolymerizing the monomer of the present invention withp-hydroxystyrene or a derivative thereof is preferably used. In thiscase, the proportion of the constitutional unit derived from the monomerof the present invention in the polymer is preferably 5% or more and ispreferably 60% or less.

When an ArF excimer laser is used as a light source, a polymer obtainedby copolymerizing the monomer of the present invention with a monomerhaving a cyclic hydrocarbon group is preferably used. Copolymerizationwith a monomer having a cyclic hydrocarbon group enables high etchingresistance.

Among them, a polymer obtained by copolymerizing the monomer of thepresent invention, a monomer having a cyclic hydrocarbon group, amonomer having a hydrophilic functional group and/or a monomer having alactone structure is preferable.

As described in the first polymer of the present invention, it is knownthat an acrylic copolymer obtained by copolymerizing a monomer having acyclic hydrocarbon group and a monomer having a hydrophilic functionalgroup, or an acrylic copolymer obtained by copolymerizing a monomerhaving a cyclic hydrocarbon group and a monomer having a lactonestructure, is preferable as a resin for the ArF excimer laserlithography. Introduction of the monomer unit of the present inventioninto these polymers enables improvement of solubility in an organicsolvent and heat resistance without impairing the resist performancesuch as high sensitivity, high resolution or high dry etchingresistance, thereby providing an excellent resist pattern with only alittle line edge roughness.

A monomer unit having a cyclic hydrocarbon group imparts high dryetching resistance to a polymer comprising the same. In particular, amonomer unit having a protecting group that is eliminated by an acid (acyclic hydrocarbon group may also be a protecting group by itself)imparts also high sensitivity to the polymer comprising the same inphotolithography using an ArF excimer laser with a wavelength of 193 nm.The monomer units having a cyclic hydrocarbon group may be of either asingle type, or two or more types, if necessary.

Examples of the monomer unit having a cyclic hydrocarbon group may bethe same as those described in the first polymer of the presentinvention, preferred examples being also the same.

A monomer unit having a hydrophilic functional group imparts adhesion toa substrate to a polymer comprising the same. In particular, a monomerunit having a protecting group that is eliminated by an acid impartsalso high sensitivity to the polymer comprising the same inphotolithography using an ArF excimer laser with a wavelength of 193 nm.Examples of a hydrophilic functional group may include a terminalhydroxy group, an alkyl-substituted ether group, δ-valerolactonyl group,and a γ-butyrolactonyl group. It should be noted that some of the abovelisted hydrophilic functional groups are generally included inhydrophobic groups. However, since even such functional groups havehydrophilicity that is needed in the present invention, they are hereindefined as a hydrophilic functional group. The monomer units having ahydrophilic functional group may be of either a single type, or two ormore types, if necessary.

Examples of the monomer unit having a hydrophilic functional group maybe the same as those described in the first polymer of the presentinvention, preferred examples being also the same.

A monomer unit having a lactone structure imparts high dry etchingresistance and adhesion to a substrate to a polymer comprising the same.

The monomer units having a lactone structure may be of either a singletype, or two or more types, if necessary.

Examples of the monomer unit having a lactone structure may be the sameas those described in the first polymer of the present invention,preferred examples being also the same.

Among them, as a resin for a chemically amplified resist composition, apolymer comprising at least one of constitutional units represented bythe formula (11) and at least one of constitutional units represented bythe formula (8), (9) or (10) is preferable. Such a polymer comprising atleast one of constitutional units represented by the formula (11) and atleast one of constitutional units represented by the formula (8), (9) or(10) will be described in the section III. The fifth polymer of thepresent invention.

The mass-average molecular weight of the third polymer of the presentinvention is not particularly limited. However, when the polymer is usedas a resin for a resist composition, the mass-average molecular weightof the third polymer of the present invention is preferably 1,000 ormore because the dry etching resistance is improved at the above range,thereby bettering the form of the resist. In addition, it is preferably100,000 or less because the solubility in a resist solution is improvedat the above range, thereby bettering the resolution.

II. The fourth Polymer of the Present Invention

The fourth polymer of the present invention comprises at least one ofconstitutional units represented by the formula (12) indicated below.The proportion of the constitutional unit represented by the followingformula (12) in the polymer is preferably 5 mol % or more.

In formula (12), W⁴ represents a direct bond or a methylene chaincontaining 1 to 6 carbon atoms [—(CH₂)_(n)— (wherein n represents aninteger of 0 to 6)], R¹⁷ represents a hydrogen atom or a methyl group,each of R¹⁸ and R¹⁹ independently represents a hydrogen atom, a linearor branched alkyl group containing 1 to 6 carbon atoms, a cyclichydrocarbon group containing 4 to 16 carbon atoms, or a linear orbranched alkyl group containing 1 to 6 carbon atoms which has a cyclichydrocarbon group containing 4 to 16 carbon atoms as a substituent; orR¹⁸ and R¹⁹ represent a cyclic hydrocarbon group containing 4 to 16carbon atoms together with the carbon atom to which they are bound. R¹⁸and R¹⁹ may be identical or may be different.

Herein, the methylene chain containing 1 to 6 carbon atoms may have, asa substituent, an alkyl group containing 1 to 3 carbon atoms which maybe optionally substituted, and may optionally have at least one etherbond therein. Further, the alkyl group and the cyclic hydrocarbon groupmay be unsubstituted, or may have at least one substituent selected froma group consisting of a linear or branched alkyl group containing 1 to 6carbon atoms which may be optionally substituted, a hydroxy group, acarboxy group, an acyl group containing 2 to 6 carbon atoms, an alkoxygroup containing 1 to 6 carbon atoms, and a carboxy group esterifiedwith an alcohol containing 1 to 6 carbon atoms. When the alkyl group andthe cyclic hydrocarbon group have two or more substituents, thesubstituents may be of either a single type, or two or more types.

Examples of a substituent on the linear or branched alkyl groupcontaining 1 to 6 carbon atoms that is the substituent on the alkylgroup and the cyclic hydrocarbon group may include a hydroxy group, acarboxy group, an acyl group containing 1 to 6 carbon atoms, and anamino group. The number of substituents may be either one, or two ormore. When the above group has two or more substituents, thesubstituents may be of either a single type, or two or more types.

Examples of W⁴ in the above formula (12) may include a direct bond(which means that the oxygen atom and the carbon atom that are adjacentto W⁴ are directly bound to each other), CH₂, CH₂CH₂, CH₂CH₂CH₂,CH(CH₃)CH₂, CH₂O, CH₂CH₂O, CH₂CH(CH₃)O, CH(CH₃)CH₂O, CH₂CH₂OCH₂CH₂O,CH₂CH(CH₃)OCH₂CH(CH₃)O, and CH(CH₃)CH₂OCH(CH₃)CH₂O.

Of these, in terms of storage stability of the polymer, a direct bond,CH₂, CH₂CH₂O and CH₂CH(CH₃)O are preferable as W⁴.

Examples of R¹⁸ and R¹⁹ in the above formula (12) may include a hydrogenatom, a methyl group, an ethyl group, a propyl group, an isopropylgroup, a butyl group, a tert-butyl group, a cyclopentyl group, acyclohexyl group, a cycloheptyl group, a 2-norbornyl group, a1-adamantyl group, a 1-adamantanemethyl group, a 1-adamantaneethylgroup, a 2-adamantyl group, a 2-adamantanemethyl group, a2-adamantaneethyl group and a 2-adamantanonyl group. Moreover, examplesof R¹⁸ and R¹⁹ may include a structure wherein these groups aresubstituted with at least one substituent selected from a groupconsisting of a linear or branched alkyl group containing 1 to 6 carbonatoms which may be optionally substituted (e.g., a hydroxy group, acarboxy group, a carboxy group esterified with an alcohol containing 1to 6 carbon atoms, an acyl group containing 1 to 6 carbon atoms, anamino group, and the like), a hydroxy group, a carboxy group, an acylgroup containing 2 to 6 carbon atoms, an alkoxy group containing 1 to 6carbon atoms, and a carboxy group esterified with an alcohol containing1 to 6 carbon atoms, or the like. The number of substituents may beeither one, or two or more. When the above group has two or moresubstituents, the substituents may be of either a single type, or two ormore types.

Further, R¹⁸ and R¹⁹ in the above formula (12) may form a cyclichydrocarbon structure containing 4 to 16 carbon atoms, together with thecarbon atom to which they are bound. Examples of such a cyclichydrocarbon structure may include an adamantylidene group and anorbornylidene group. Furthermore, examples of such a cyclic hydrocarbonstructure may also include those wherein the cyclic hydrocarbonstructure containing 4 to 16 carbon atoms is substituted with at leastone substituent selected from a group consisting of a linear or branchedalkyl group containing 1 to 6 carbon atoms which may be optionallysubstituted (e.g., a hydroxy group, a carboxy group, a carboxy groupesterified with an alcohol containing 1 to 6 carbon atoms, an acyl groupcontaining 1 to 6 carbon atoms, an amino group, and the like), a hydroxygroup, a carboxy group, an acyl group containing 2 to 6 carbon atoms, analkoxy group containing 1 to 6 carbon atoms, and a carboxy groupesterified with an alcohol containing 1 to 6 carbon atoms, or the like.The number of substituents may be either one, or two or more. When theabove structure has two or more substituents, the substituents may be ofeither a single type, or two or more types.

In terms of having excellent dry etching resistance when the polymer isused for a resist composition, as the constitutional unit represented bythe above formula (12), a constitutional unit wherein R¹⁸ represents abridged cyclic hydrocarbon group containing 4 to 16 carbon atoms, suchas a 2-norbornyl group, a 1-adamantyl group, a 1-adamantanemethyl group,a 1-adamantaneethyl group, a 2-adamantyl group, a 2-adamantanemethylgroup, a 2-adamantaneethyl group or a 2-adamantanonyl group, or a linearor branched alkyl group containing 1 to 6 carbon atoms having as asubstituent the bridged cyclic hydrocarbon group containing 4 to 16carbon atoms, and R¹⁹ represents a hydrogen atom, or a linear orbranched alkyl group containing 1 to 6 carbon atoms, is preferable. Inparticular, a constitutional unit wherein R¹⁸ represents a 2-norbornylgroup or a 1-adamantyl group, and R¹⁹ represents a methyl group or anethyl group, is more preferable. Moreover, a constitutional unit whereinR¹⁸ and R¹⁹ form an adamantylidene group or a norbornylidene grouptogether with the carbon atom to which they are bound, is alsopreferable.

Furthermore, as stated above, in the above compounds, an alkyl groupand/or a cyclic hydrocarbon group may be substituted with a linear orbranched alkyl group containing 1 to 6 carbon atoms which may beoptionally substituted (e.g., a hydroxy group, a carboxy group, acarboxy group esterified with an alcohol containing 1 to 6 carbon atoms,an acyl group containing 1 to 6 carbon atoms, an amino group, and thelike), a hydroxy group, a carboxy group, an acyl group containing 2 to 6carbon atoms, an alkoxy group containing 1 to 6 carbon atoms, a carboxygroup esterified with an alcohol containing 1 to 6 carbon atoms, or thelike. The number of substituents may be either one, or two or more. Whenthe above compound has two or more substituents, the substituents may beof either a single type, or two or more types.

Of these, a linear or branched alkyl group containing 1 to 6 carbonatoms which may be optionally substituted, a hydroxy group, a carboxygroup, an acyl group containing 2 to 6 carbon atoms, an alkoxy groupcontaining 1 to 6 carbon atoms, and a carboxy group esterified with analcohol containing 1 to 6 carbon atoms are preferable as a substituent,in terms of having excellent light transparency when the polymer is usedfor a resist composition. Moreover, in terms of having excellent dryetching resistance when the polymer is used for a resist composition, amethyl group and an ethyl group are more preferable as a substituent.And, in terms of having excellent adhesion of the polymer to a substratewhen the polymer is used for a resist composition, a hydroxyl group, ahydroxymethyl group, and a hydroxyethyl group are more preferable as asubstituent.

The fourth polymer of the present invention comprising at least one ofconstitutional units represented by the above formula (12) is obtainedby (co)polymerizing a monomer composition comprising a monomerrepresented by the following formula (II):

W⁴, R¹⁷, R¹⁸ and R¹⁹ in the formula (II) correspond to W⁴, R¹⁷, R¹⁸ andR¹⁹ in the formula (12), respectively.

Examples of the monomer represented by the above formula (11) mayinclude monomers represented by the formulas (II-1) to (III-18)indicated below. In the formulas (II-1) to (II-18), R¹⁷ is the same asin the above formula (II), and it represents a hydrogen atom or a methylgroup.

Among the monomers represented by the above formula (II), thoserepresented by the above formulas (II-1) to (II-9) are preferable interms of having excellent dry etching resistance when the polymer isused for a resist composition.

The monomer represented by the above formula (II) can be produced, forexample, by following the process (Scheme 2) indicated below.

A raw material ketone such as 2-adamantanone, 1-adamantyl methyl ketone,norcampher and derivatives thereof are commercially available, or theycan be synthesized by a known production method, and all of them can beused.

A method of synthesizing a cyclic acetal from a ketone and a diol or ahydroxycarboxylic acid under acid conditions is widely known. A lowpolar solvent such as toluene, cyclohexane or hexane is preferably usedas a reaction solvent. Moreover, in advance of the reaction, watercontained in the reaction system is preferably removed so as to increaseyield.

The esterification reaction of the alcohol can be carried out undercommon esterification conditions. Examples of a reactant may include a(meth)acrylic halide, a (meth)acrylic anhydride, a (meth)acrylic esterand (meth)acrylic acid. Moreover, a catalyst used in esterification,such as an acid, a base, a Lewis acid or an enzyme, may be used.

In some cases, the product of this reaction may comprise severalconstitutional isomers, geometric isomers or optical isomers. In thepresent invention, both a mixture consisting of such isomers and aproduct containing an intermediate can be used. If necessary, theobtained reaction product may be purified by a known method such asdistillation, short-path distillation, recrystallization or columnchromatography.

The fourth polymer of the present invention may be a homopolymerconsisting of one type of the monomer represented by the above formula(II), a copolymer consisting of two or more types of the monomerrepresented by the above formula (II), or a copolymer consisting of atleast one type of the monomer represented by the above formula (II) andat least one type of monomers other than the monomer represented by theabove formula (II). When the fourth polymer of the present invention isa copolymer, each constitutional unit can have any given sequence.Accordingly, this polymer may be a random copolymer, an alternatingcopolymer, or a block copolymer.

In the present invention, at least one type of the monomer representedby the above formula (II) may be copolymerized with at least one type ofknown monomers other than the above monomer. Examples of a monomercapable of being copolymerized may include those that are conventionallyknown as a positive resist, a negative resist, an anti-reflection coatmaterial or an insulating film-forming material. For example, themonomer capable of being copolymerized may include a known monomer suchas an acrylic acid derivative and a methacrylic acid derivative, whichhave a dry etching resistance-improving group or a soluble groupinvolving acid dissociation, a carboxylic acid (including a derivativethereof) having an ethylene double bond causing alkali solubility, andknown monomers used in the production of an acrylic resin. Specificexamples of a monomer capable of being copolymerized may be the same asthose described in the first polymer of the present invention.

The fourth polymer of the present invention is preferably used as amaterial for a resist composition, and particularly as a material for achemically amplified resist composition. Hereinafter, a case where thefourth polymer of the present invention is a resin used for a chemicallyamplified resist composition will be explained.

As described in the first polymer of the present invention, the resinfor a chemically amplified resist composition is required to have both aproperty for becoming soluble in an alkaline aqueous solution by an acidso as to realize high sensitivity and a structure having high carbondensity so as to realize high dry etching resistance. The fourth polymerof the present invention is excellent in solubility in an organicsolvent and heat resistance, and has little line edge roughness. When astructure having a property for becoming soluble in an alkaline aqueoussolution by the action of an acid, or a structure having high dryetching resistance is introduced into such a polymer, an excellent resinfor a chemically amplified resist composition can be obtained.

Examples of the structure having a functional group that is easilyeliminated by the action of an acid and the structure having high carbondensity may be the same as those described in the first polymer of thepresent invention.

In order to introduce the structure having a functional group that iseasily eliminated by the action of an acid or the structure having highcarbon density into the polymer, the monomer of the present inventionmay be copolymerized with a monomer having such a structure.

As a monomer having such a structure, for example, the one that is knownas a raw material monomer for a resin for a chemically amplified resistcomposition can be used. A raw material monomer used for the polymer ofthe present invention is arbitrarily selected depending on light sourceused in lithography.

For example, when a KrF excimer laser or an electron beam is used as alight source, considering its high etching resistance, a polymerobtained by copolymerizing the monomer of the present invention withp-hydroxystyrene or a derivative thereof is preferably used. In thiscase, the proportion of the constitutional unit derived from the monomerof the present invention in the polymer is preferably 5% or more and ispreferably 60% or less.

When an ArF excimer laser is used as a light source, a polymer obtainedby copolymerizing the monomer of the present invention with a monomerhaving a cyclic hydrocarbon group is preferably used. Copolymerizationwith a monomer having a cyclic hydrocarbon group enables high etchingresistance.

Among them, a polymer obtained by copolymerizing the monomer of thepresent invention, a monomer having a cyclic hydrocarbon group, amonomer having a hydrophilic functional group and/or a monomer having alactone structure is preferable.

As described in the first polymer of the present invention, it is knownthat an acrylic copolymer obtained by copolymerizing a monomer having acyclic hydrocarbon group and a monomer having a hydrophilic functionalgroup, or an acrylic copolymer obtained by copolymerizing a monomerhaving a cyclic hydrocarbon group and a monomer having a lactonestructure, is preferable as a resin for the ArF excimer laserlithography. Introduction of the monomer unit of the present inventioninto these polymers enables improvement of solubility in an organicsolvent and heat resistance without impairing the resist performancesuch as high sensitivity, high resolution or high dry etchingresistance, thereby providing an excellent resist pattern with only alittle line edge roughness.

A monomer unit having a cyclic hydrocarbon group imparts high dryetching resistance to a polymer comprising the same. In particular, amonomer unit having a protecting group that is eliminated by an acid (acyclic hydrocarbon group may also be a protecting group by itself)imparts also high sensitivity to the polymer comprising the same inphotolithography using an ArF excimer laser with a wavelength of 193 nm.The monomer units having a cyclic hydrocarbon group may be of either asingle type, or two or more types, if necessary.

Examples of the monomer unit having a cyclic hydrocarbon group may bethe same as those described in the first polymer of the presentinvention, preferred examples being also the same.

A monomer unit having a hydrophilic functional group imparts adhesion toa substrate to a polymer comprising the same. In particular, a monomerunit having a protecting group that is eliminated by an acid impartsalso high sensitivity to the polymer comprising the same inphotolithography using an ArF excimer laser with a wavelength of 193 nm.Examples of a hydrophilic functional group may include a terminalhydroxy group, an alkyl-substituted ether group, a δ-valerolactonylgroup, and a γ-butyrolactonyl group. It should be noted that some of theabove listed hydrophilic functional groups are generally included inhydrophobic groups. However, since even such functional groups havehydrophilicity that is needed in the present invention, they are hereindefined as a hydrophilic functional group. The monomer units having ahydrophilic functional group may be of either a single type, or two ormore types, if necessary.

Examples of the monomer unit having a hydrophilic functional group maybe the same as those described in the first polymer of the presentinvention, preferred examples being also the same.

A monomer unit having a lactone structure imparts high dry etchingresistance and adhesion to a substrate to a polymer comprising the same.The monomer units having a lactone structure may be of either a singletype, or two or more types, if necessary.

Examples of the monomer unit having a lactone structure may be the sameas those described in the first polymer of the present invention,preferred examples being also the same.

Among them, as a resin for a chemically amplified resist composition, apolymer comprising at least one of constitutional units represented bythe formula (12) and at least one of constitutional units represented bythe formula (8), (9) or (10) is preferable. Such a polymer comprising atleast one of constitutional units represented by the formula (12) and atleast one of constitutional units represented by the formula (8), (9) or(10) will be described in the section III. The fifth polymer of thepresent invention.

The mass-average molecular weight of the fourth polymer of the presentinvention is not particularly limited. However, when the polymer is usedas a resin for a resist composition, the mass-average molecular weightof the fourth polymer of the present invention is preferably 1,000 ormore because the dry etching resistance is improved at the above range,thereby bettering the form of the resist. In addition, it is preferably100,000 or less because the solubility in a resist solution is improvedat the above range, thereby bettering the resolution.

III. The Fifth Polymer of the Present Invention

The fifth polymer of the present invention comprises at least one ofconstitutional units represented by the following formula (13) and atleast one of constitutional units represented by the following formula(8), (9) or (10):

In formula (13), W⁵ represents a direct bond or a methylene chaincontaining 1 to 6 carbon atoms [—(CH₂)_(x)— (wherein x represents aninteger of 0 to 6)], W⁶ represents a direct bond or a methylene chaincontaining 1 to 3 carbon atoms [—(CH₂)_(y)— (wherein y represents aninteger of 0 to 3)], W⁷ represents a methylene chain containing 1 to 3carbon atoms [—(CH₂)_(z)— (wherein z represents an integer of 1 to 3)],R²⁰ represents a hydrogen atom or a methyl group, each of R²¹ and R²²independently represents a hydrogen atom, a linear or branched alkylgroup containing 1 to 6 carbon atoms, a cyclic hydrocarbon groupcontaining 4 to 16 carbon atoms, or a linear or branched alkyl groupcontaining 1 to 6 carbon atoms which has a cyclic hydrocarbon groupcontaining 4 to 16 carbon atoms as a substituent; or R²¹ and R²²represent a cyclic hydrocarbon group containing 4 to 16 carbon atomstogether with the carbon atom to which they are bound. R²¹ and R²² maybe identical or may be different.

Herein, the methylene chain containing 1 to 6 carbon atoms may have, asa substituent, an alkyl group containing 1 to 3 carbon atoms which maybe optionally substituted, and may optionally have at least one etherbond therein. The methylene chain containing 1 to 3 carbon atoms mayhave a carbonyl group therein. Further, the alkyl group and the cyclichydrocarbon group may be unsubstituted, or may have at least onesubstituent selected from a group consisting of a linear or branchedalkyl group containing 1 to 6 carbon atoms which may be optionallysubstituted, a hydroxy group, a carboxy group, an acyl group containing2 to 6 carbon atoms, an alkoxy group containing 1 to 6 carbon atoms, anda carboxy group esterified with an alcohol containing 1 to 6 carbonatoms. When the alkyl group and the cyclic hydrocarbon group have two ormore substituents, the substituents may be of either a single type, ortwo or more types.

In formula (8), R⁸ represents a hydrogen atom or a methyl group, and R⁹represents a linear or branched alkyl group containing 1 to 6 carbonatoms, a cyclic hydrocarbon group containing 4 to 8 carbon atoms, or abridged cyclic hydrocarbon group containing 4 to 16 carbon atoms.

Herein, the alkyl group, the cyclic hydrocarbon group and the bridgedcyclic hydrocarbon group may be unsubstituted, or may have at least onesubstituent selected from a group consisting of a linear or branchedalkyl group containing 1 to 6 carbon atoms which may be optionallysubstituted, a hydroxy group, a carboxy group, and a carboxy groupesterified with an alcohol containing 1 to 6 carbon atoms. When thealkyl group, the cyclic hydrocarbon group and the bridged cyclichydrocarbon group have two or more substituents, the substituents may beof either a single type, or two or more types.

In formula (9), R¹⁰ represents a hydrogen atom or a methyl group, andR¹¹ represents a hydrogen atom, a hydrophilic functional group, a linearor branched alkyl group containing 1 to 6 carbon atoms which has ahydrophilic functional group, a cyclic hydrocarbon group containing 4 to8 carbon atoms which has a hydrophilic functional group, or a bridgedcyclic hydrocarbon group containing 4 to 16 carbon atoms which has ahydrophilic functional group.

Herein, the alkyl group, the cyclic hydrocarbon group, the bridgedcyclic hydrocarbon group and the hydrophilic functional group may beunsubstituted, or may have at least one substituent selected from agroup consisting of a linear or branched alkyl group containing 1 to 6carbon atoms which may be optionally substituted, a hydroxy group, acarboxy group, and a carboxy group esterified with an alcohol containing1 to 6 carbon atoms. When the alkyl group, the cyclic hydrocarbon group,the bridged cyclic hydrocarbon group and the hydrophilic functionalgroup have two or more substituents, the substituents may be of either asingle type, or two or more types.

Examples of a hydrophilic functional group in the formula (9) mayinclude groups with high polarity, such as a hydroxyl group, a carboxygroup or an amino group; linear or branched alkyl groups having astructure such as ketone, acid anhydride, ester, ether, lactone, imideor amide; and cyclic compounds. Compounds having a hydrophilicfunctional group may include monocyclic saturated hydrocarbon groupscontaining 4 to 8 carbon atoms or a bridged cyclic hydrocarbon groupscontaining 4 to 16 carbon atoms, a portion of the skeleton of which issubstituted with a structure such as ketone, acid anhydride, ester,ether, lactone, imide or amide. Some of the above listed hydrophilicfunctional groups are generally included in hydrophobic groups. However,since even such functional groups have hydrophilicity that is needed fora resist composition of the present invention, they are herein definedas a hydrophilic functional group.

In formula (10), each of R¹² and R¹³ independently represents a hydrogenatom, a methyl group or an ethyl group, and q represents an integer of 1to 4. R¹² and R¹³ may be identical or may be different.

Herein, C_(q)H_(2q) represents a methylene chain containing 1 to 4carbon atoms [—(CH₂)_(q)— (wherein q represents an integer of 1 to 4)].

In the fifth polymer of the present invention, the constitutional units(13), (8), (9) and (10) are not necessarily of the same type, but two ormore types may be mixed therein as long as they are represented by theabove general formulas. Moreover, in this polymer, each constitutionalunit can have any given sequence. Accordingly, this polymer may be arandom copolymer, an alternating copolymer, or a block copolymer.

Examples of a substituent on the linear or branched alkyl groupcontaining 1 to 6 carbon atoms that is the substituent on the alkylgroup, the cyclic hydrocarbon group, the bridged cyclic hydrocarbongroup and the hydrophilic functional group, may include a hydroxy group,a carboxy group, an acyl group containing 1 to 6 carbon atoms, and anamino group. The number of substituents may be either one, or two ormore. When the above group has two or more substituents, thesubstituents may be of either a single type, or two or more types.

Examples of W⁵ in the above formula (13) may include a direct bond(which means that the oxygen atom and the carbon atom that are adjacentto W⁶ are directly bound to each other), CH₂, CH₂CH₂, CH₂CH₂CH₂,CH(CH₃)CH₂, CH₂O, CH₂CH₂O, CH₂CH(CH₃)O, CH(CH₃)CH₂O, CH₂CH₂OCH₂CH₂O,CH₂CH(CH₃)OCH₂CH(CH₃)O, and CH(CH₃)CH₂OCH(CH₃)CH₂O.

Of these, in terms of storage stability of the polymer, a direct bond,CH₂, CH₂CH₂O and CH₂CH(CH₃)O are preferable as W⁵.

Examples of W⁶ in the above formula (13) may include a direct bond(which means that the oxygen atom and the carbon atom that are adjacentto W⁶ are directly bound to each other), CH₂, C(O), CH₂CH₂, CH₂C(O),CH₂CH₂CH₂, and CH₂C(O)CH₂.

Of these, in terms of storage stability of the polymer, a direct bond,CH₂, C(O) and CH₂C(O) are preferable as W⁶.

Examples of W⁷ in the above formula (13) may include CH₂, C(O), CH₂CH₂,CH₂C(O), CH₂CH₂CH₂, and CH₂C(O)CH₂.

Of these, in terms of storage stability of the polymer, CH₂, C(O) andCH₂C(O) are preferable as W⁷.

Examples of R²¹ and R²² in the above formula (13) may include a hydrogenatom, a methyl group, an ethyl group, a propyl group, an isopropylgroup, a butyl group, a tert-butyl group, a cyclopentyl group, acyclohexyl group, a cycloheptyl group, a 2-norbornyl group, a1-adamantyl group, a 1-adamantanemethyl group, a 1-adamantaneethylgroup, a 2-adamantyl group, a 2-adamantanemethyl group, a2-adamantaneethyl group and a 2-adamantanonyl group. Moreover, examplesof R²¹ and R²² may include a structure wherein these groups aresubstituted with at least one substituent selected from a groupconsisting of a linear or branched alkyl group containing 1 to 6 carbonatoms which may be optionally substituted (e.g., a hydroxy group, acarboxy group, a carboxy group esterified with an alcohol containing 1to 6 carbon atoms, an acyl group containing 1 to 6 carbon atoms, anamino group, and the like), a hydroxy group, a carboxy group, an acylgroup containing 2 to 6 carbon atoms, an alkoxy group containing 1 to 6carbon atoms, and a carboxy group esterified with an alcohol containing1 to 6 carbon atoms, or the like. The number of substituents may beeither one, or two or more. When the above group has two or moresubstituents, the substituents may be of either a single type, or two ormore types.

Further, R²¹ and R²² in the above formula (13) may form a cyclichydrocarbon structure containing 4 to 16 carbon atoms, together with thecarbon atom to which they are bound. Examples of such a cyclichydrocarbon structure may include an adamantylidene group, anorbornylidene group, and a cyclohexylidene group. Furthermore, examplesof such a cyclic hydrocarbon structure may also include those whereinthe cyclic hydrocarbon structure containing 4 to 16 carbon atoms issubstituted with at least one substituent selected from a groupconsisting of a linear or branched alkyl group containing 1 to 6 carbonatoms which may be optionally substituted (e.g., a hydroxy group, acarboxy group, a carboxy group esterified with an alcohol containing 1to 6 carbon atoms, an acyl group containing 1 to 6 carbon atoms, anamino group, and the like), a hydroxy group, a carboxy group, an acylgroup containing 2 to 6 carbon atoms, an alkoxy group containing 1 to 6carbon atoms, and a carboxy group esterified with an alcohol containing1 to 6 carbon atoms, or the like. The number of substituents may beeither one, or two or more. When the above structure has two or moresubstituents, the substituents may be of either a single type, or two ormore types.

As the constitutional unit represented by the above formula (13), aconstitutional unit wherein R²¹ represents a hydrogen atom, a methylgroup or an ethyl group and R²² represents a cyclopentyl group, acyclohexyl group or a cycloheptyl group, and a constitutional unitwherein R²¹ and R²² form a cyclic hydrocarbon group containing 5 to 12carbon atoms together with the carbon atom to which they are bound, arepreferable. Among them, the constitutional unit represented by the aboveformula (11) and the constitutional unit represented by the aboveformula (12), are particularly preferable.

The constitutional unit represented by the above formula (8) is obtainedby copolymerizing a monomer such as cyclohexyl (meth)acrylate,1-isobornyl (meth)acrylate, adamantyl (meth)acrylate, tricyclodecanyl(meth)acrylate, dicyclopentyl (meth)acrylate,2-(meth)acryloyloxy-2-methyladamantane,2-(meth)acryloyloxy-2-ethyladamantane, or derivatives having asubstituent such as an alkyl group, a hydroxy group or a carboxy groupon the cyclic hydrocarbon group of these monomers.

In terms of sensitivity and resolution when the polymer is used as aresist composition material, a constitutional unit derived from2-(meth)acryloyloxy-2-methyladamantane, and a constitutional unitderived from 2-(meth)acryloyloxy-2-ethyladamantane are preferable, asthe constitutional unit represented by the above formula (8).

The constitutional unit represented by the above formula (9) is obtainedby copolymerizing a monomer having a hydrophilic functional group, suchas (meth)acrylate having a terminal hydroxy group, (meth)acrylate havingan alkyl-substituted ether group, (meth)acrylate having aδ-valerolactonyl group, or (meth)acrylate having a γ-butyrolactonylgroup; derivatives having a substituent such as an alkyl group, ahydroxy group or a carboxy group on the hydrophilic functional group ofthese monomers; or a monomer having a hydrophilic functional group suchas a hydroxy group or a carboxy group on the cyclic hydrocarbon group ofa monomer such as cyclohexyl (meth)acrylate, 1-isobornyl (meth)acrylate,adamantyl (meth)acrylate, tricyclodecanyl (meth)acrylate, dicyclopentyl(meth)acrylate, 2-(meth)acryloyloxy-2-methyladamantane or2-(meth)acryloyloxy-2-ethyladamantane. Specific examples of such amonomer may include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl(meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-methoxyethyl(meth)acrylate, 2-ethoxyethyl (meth)acrylate,1-methacryloyloxy-3-hydroxyadamantane,β-(meth)acryloyloxy-β-methyl-δ-valerolactone,β-(meth)acryloyloxy-γ-butyrolactone,β-(meth)acryloyloxy-β-methyl-γ-butyrolactone,α-(meth)acryloyloxy-γ-butyrolactone,2-(1-(meth)acryloyloxy)ethyl-4-butanolide, pantolactone (meth)acrylate,8-methacryloyloxy-3-oxatricyclo[5.2.1.0^(2,6)]decan-2-one, and9-methacryloyloxy-3-oxatricyclo[5.2.1.0^(2,6)]decan-2-one.

In terms of adhesion to a substrate when the polymer is used as a resistcomposition material, a constitutional unit derived from1-methacryloyloxy-3-hydroxyadamantane, a constitutional unit derivedfrom 8-methacryloyloxy-3-oxatricyclo[5.2.1.0^(2,6)]decan-2-one, and aconstitutional unit derived from9-methacryloyloxy-3-oxatricyclo[5.2.1.0^(2,6)]decan-2-one arepreferable, as the constitutional unit represented by the above formula(9).

The constitutional unit represented by the above formula (10) isobtained by copolymerizing a monomer such as 4-8 memberedα-methylenelactone, or derivatives having a substituent such as an alkylgroup, a hydroxy group or a carboxy group on a carbon of the lactonering of these monomers.

In terms of sensitivity and resolution when the polymer is used as aresist composition material, a constitutional unit derived fromα-methylene-γ-butyrolactone, and a constitutional unit derived from itsderivatives having a substituent such as a methyl group or an ethylgroup on the carbon of the γ position, for example,α-methylene-γ-butyrolactone, α-methylene-γ-methyl-γ-butyrolactone,α-methyleney-ethyl-γ-butyrolactone, and4,4-dimethyl-2-methylene-4-butanolide, are preferable, as theconstitutional unit represented by the above formula (10).

In order to improve solubility of the polymer in an organic solvent andheat resistance and to reduce line edge roughness, the proportion of theconstitutional unit represented by the above formula (13) is preferably5 mol % or more in the polymer. Moreover, in order not to reducesensitivity and resolution, the proportion of the constitutional unitrepresented by the above formula (13) is preferably 50 mol % or less inthe polymer.

In order to improve sensitivity and resolution, the proportion of theconstitutional unit represented by the above formula (8) is preferably30 mol % or more in the polymer. Moreover, in order not to reducesolubility of the polymer in an organic solvent, the proportion of theconstitutional unit represented by the above formula (8) is preferably70 mol % or less in the polymer.

In order not to reduce dry etching resistance, the proportion of theconstitutional unit represented by the above formula (9) is preferably70 mol % or less in the polymer.

In order not to reduce sensitivity and resolution, the proportion of theconstitutional unit represented by the above formula (10) is preferably60 mol % or less in the polymer.

The fifth polymer of the present invention is preferably used as amaterial for a resist composition, and particularly as a material for achemically amplified resist composition. The fifth polymer of thepresent invention is particularly excellent in sensitivity, resolution,and the like.

Moreover, the fifth polymer of the present invention may comprise atleast one type of constitutional units derived from known monomers otherthan the constitutional units represented by the above formulas (13) and(8) to (10). Specific examples of a monomer capable of beingcopolymerized or a constitutional unit may be the same as thosedescribed in the first polymer of the present invention.

The mass-average molecular weight of the fifth polymer of the presentinvention is not particularly limited. However, when the polymer is usedas a resin for a resist composition, the mass-average molecular weightof the fifth polymer of the present invention is preferably 1,000 ormore because the dry etching resistance is improved at the above range,thereby bettering the form of the resist. In addition, it is preferably100,000 or less because the solubility in a resist solution is improvedat the above range, thereby bettering the resolution.

6. Other Polymers for a Resist Used for the Resist Composition of thePresent Invention

As a polymer for a resist used for the resist composition of the presentinvention, a polymer comprising at least one of constitutional unitsrepresented by the above formula (7) other than the second polymer ofthe present invention (the sixth polymer), or a polymer comprising atleast one of constitutional units represented by the above formula (13)other than the fifth polymer of the present invention (the seventhpolymer), may also be used. The resist composition of the presentinvention containing at least one polymer comprising at least one ofconstitutional units represented by the above formula (7), and theresist composition of the present invention containing at least onepolymer comprising at least one of constitutional units represented bythe above formula (13), also have sufficient sensitivity, resolution anddry etching resistance, while having little line edge roughness.

I. The Sixth Polymer of the Present Invention

The sixth polymer of the present invention comprises at least one ofconstitutional units represented by the formula (7) indicated below. Thesixth polymer of the present invention may be a homopolymer consistingof one type of the constitutional unit represented by the followingformula (7), a copolymer consisting of two or more types of theconstitutional unit represented by the following formula (7), or acopolymer consisting of at least one type of the constitutional unitrepresented by the following formula (7) and at least one type ofconstitutional unit other than the constitutional unit represented bythe following formula (7). When the sixth polymer of the presentinvention is a copolymer, each constitutional unit can have any givensequence. Accordingly, this polymer may be a random copolymer, analternating copolymer, or a block copolymer. The proportion of theconstitutional unit represented by the following formula (7) in thepolymer is preferably 5 mol % or more.

In formula (7), each of R⁶ and R⁷ independently represents a hydrogenatom, a linear or branched alkyl group containing 1 to 6 carbon atoms, acyclic hydrocarbon group containing 4 to 16 carbon atoms, or a linear orbranched alkyl group containing 1 to 6 carbon atoms which has a cyclichydrocarbon group containing 4 to 16 carbon atoms as a substituent; orR⁶ and R⁷ represent a cyclic hydrocarbon group containing 4 to 16 carbonatoms together with the carbon atom to which they are bound. R⁶ and R⁷may be identical or may be different.

Herein, the alkyl group and the cyclic hydrocarbon group may beunsubstituted, or may have at least one substituent selected from agroup consisting of a linear or branched alkyl group containing 1 to 6carbon atoms which may be optionally substituted, a hydroxy group, acarboxy group, an acyl group containing 2 to 6 carbon atoms, an alkoxygroup containing 1 to 6 carbon atoms, and a carboxy group esterifiedwith an alcohol containing 1 to 6 carbon atoms. When the alkyl group andthe cyclic hydrocarbon group have two or more substituents, thesubstituents may be of either a single type, or two or more types.

Examples of a substituent on the linear or branched alkyl groupcontaining 1 to 6 carbon atoms that is the substituent on the alkylgroup and the a cyclic hydrocarbon group may include a hydroxy group, acarboxy group, an acyl group containing 1 to 6 carbon atoms, and anamino group. The number of substituents may be either one, or two ormore. When the above group has two or more substituents, thesubstituents may be of either a single type, or two or more types.

Examples of R⁶ and R⁷ in the above formula (7) may include a hydrogenatom, a methyl group, an ethyl group, a propyl group, an isopropylgroup, a butyl group, a tert-butyl group, a cyclopentyl group, acyclohexyl group, a cycloheptyl group, a 2-norbornyl group, a1-adamantyl group, a 1-adamantanemethyl group, a 1-adamantaneethylgroup, a 2-adamantyl group, a 2-adamantanemethyl group, a2-adamantaneethyl group and a 2-adamantanonyl group. Moreover, R⁶ and R⁷may include a structure wherein these groups are substituted with atleast one substituent selected from a group consisting of a linear orbranched alkyl group containing 1 to 6 carbon atoms which may beoptionally substituted (e.g., a hydroxy group, a carboxy group, acarboxy group esterified with an alcohol containing 1 to 6 carbon atoms,an acyl group containing 1 to 6 carbon atoms, an amino group, and thelike), a hydroxy group, a carboxy group, an acyl group containing 2 to 6carbon atoms, an alkoxy group containing 1 to 6 carbon atoms, and acarboxy group esterified with an alcohol containing 1 to 6 carbon atoms,or the like. The number of substituents may be either one, or two ormore. When the above group has two or more substituents, thesubstituents may be of either a single type, or two or more types.

Moreover, R⁶ and R⁷ in the above formula (7) may form a cyclichydrocarbon structure containing 4 to 16 carbon atoms, together with thecarbon atom to which they are bound. Examples of such a cyclichydrocarbon structure may include an adamantylidene group, anorbornylidene group, and a cyclohexylidene group. Furthermore, examplesof such a cyclic hydrocarbon structure may also include those whereinthe cyclic hydrocarbon structure containing 4 to 16 carbon atoms issubstituted with at least one substituent selected from a groupconsisting of a linear or branched alkyl group containing 1 to 6 carbonatoms which may be optionally substituted (e.g., a hydroxy group, acarboxy group, a carboxy group esterified with an alcohol containing 1to 6 carbon atoms, an acyl group containing 1 to 6 carbon atoms, anamino group, and the like), a hydroxy group, a carboxy group, an acylgroup containing 2 to 6 carbon atoms, an alkoxy group containing 1 to 6carbon atoms, and a carboxy group esterified with an alcohol containing1 to 6 carbon atoms, or the like. The number of substituents may beeither one, or two or more. When the structure has two or moresubstituents, the substituents may be of either a single type, or two ormore types.

As the constitutional unit represented by the above formula (7), aconstitutional unit wherein R⁶ represents a hydrogen atom, a methylgroup or an ethyl group and R⁷ represents a cyclopentyl group, acyclohexyl group or a cycloheptyl group, and a constitutional unitwherein R⁶ and R⁷ form a cyclic hydrocarbon group containing 5 to 8carbon atoms together with the carbon atom to which they are bound, arepreferable.

The sixth polymer of the present invention may comprise at least onetype of constitutional units other than the constitutional unitrepresented by the above formula (7). Examples of a monomer capable ofbeing copolymerized in the sixth polymer of the present invention mayinclude those that are conventionally known as a positive resist, anegative resist, an anti-reflection coat material or an insulatingfilm-forming material. For example, the monomer capable of beingcopolymerized may include a known monomer such as an acrylic acidderivative and a methacrylic acid derivative, which have a dry etchingresistance-improving group or a soluble group involving aciddissociation, a carboxylic acid (including a derivative thereof) havingan ethylene double bond causing alkali solubility, and known monomersused in the production of an acrylic resin. Specific examples of amonomer capable of being copolymerized may be the same as thosedescribed in the first polymer of the present invention.

As described in the first polymer of the present invention, the resinfor a chemically amplified resist composition is required to have both aproperty for becoming soluble in an alkaline aqueous solution by an acidso as to realize high sensitivity and a structure having high carbondensity so as to realize high dry etching resistance. The sixth polymerof the present invention is excellent in solubility in an organicsolvent and heat resistance, and has little line edge roughness. When astructure having a property for becoming soluble in an alkaline aqueoussolution by the action of an acid, or a structure having high dryetching resistance is introduced into such a polymer, an excellent resinfor a chemically amplified resist composition can be obtained.

Examples of the structure having a functional group that is easilyeliminated by the action of an acid and the structure having high carbondensity may be the same as those described in the first polymer of thepresent invention.

In order to introduce the structure having a functional group that iseasily eliminated by the action of an acid or the structure having highcarbon density into the polymer, the monomer of the present inventionmay be copolymerized with a monomer having such a structure.

As a monomer having such a structure, for example, the one that is knownas a raw material monomer for a resin for a chemically amplified resistcomposition can be used. A raw material monomer used for the polymer ofthe present invention is arbitrarily selected depending on light sourceused in lithography.

For example, when a KrF excimer laser or an electron beam is used as alight source, considering its high etching resistance, a polymerobtained by copolymerizing the monomer of the present invention withp-hydroxystyrene or a derivative thereof is preferably used. In thiscase, the proportion of the constitutional unit derived from the monomerof the present invention in the polymer is preferably 5% or more and ispreferably 60% or less.

When an ArF excimer laser is used as a light source, a polymer obtainedby copolymerizing the monomer of the present invention with a monomerhaving a cyclic hydrocarbon group is preferably used. Copolymerizationwith a monomer having a cyclic hydrocarbon group enables high etchingresistance.

Among them, a polymer obtained by copolymerizing the monomer of thepresent invention, a monomer having a cyclic hydrocarbon group, amonomer having a hydrophilic functional group and/or a monomer having alactone structure is preferable.

As described in the first polymer of the present invention, it is knownthat an acrylic copolymer obtained by copolymerizing a monomer having acyclic hydrocarbon group and a monomer having a hydrophilic functionalgroup, or an acrylic copolymer obtained by copolymerizing a monomerhaving a cyclic hydrocarbon group and a monomer having a lactonestructure, is preferable as a resin for the ArF excimer laserlithography. Introduction of the monomer unit of the present inventioninto these polymers enables improvement of solubility in an organicsolvent and heat resistance without impairing the resist performancesuch as high sensitivity, high resolution or high dry etchingresistance, thereby providing an excellent resist pattern with only alittle line edge roughness.

A monomer unit having a cyclic hydrocarbon group imparts high dryetching resistance to a polymer comprising the same. In particular, amonomer unit having a protecting group that is eliminated by an acid (acyclic hydrocarbon group may also be a protecting group by itself)imparts also high sensitivity to the polymer comprising the same inphotolithography using an ArF excimer laser with a wavelength of 193 nm.The monomer units having a cyclic hydrocarbon group may be of either asingle type, or two or more types, if necessary.

Examples of the monomer unit having a cyclic hydrocarbon group may bethe same as those described in the first polymer of the presentinvention, preferred examples being also the same.

A monomer unit having a hydrophilic functional group imparts adhesion toa substrate to a polymer comprising the same. In particular, a monomerunit having a protecting group that is eliminated by an acid impartsalso high sensitivity to the polymer comprising the same inphotolithography using an ArF excimer laser with a wavelength of 193 nm.Examples of a hydrophilic functional group may include a terminalhydroxy group, an alkyl-substituted ether group, a δ-valerolactonylgroup, and a γ-butyrolactonyl group. It should be noted that some of theabove listed hydrophilic functional groups are generally included inhydrophobic groups. However, since even such functional groups havehydrophilicity that is needed in the present invention, they are hereindefined as a hydrophilic functional group. The monomer units having ahydrophilic functional group may be of either a single type, or two ormore types, if necessary.

Examples of the monomer unit having a hydrophilic functional group maybe the same as those described in the first polymer of the presentinvention, preferred examples being also the same.

A monomer unit having a lactone structure imparts high dry etchingresistance and adhesion to a substrate to a polymer comprising the same.

The monomer units having a lactone structure may be of either a singletype, or two or more types, if necessary.

Examples of the monomer unit having a lactone structure may be the sameas those described in the first polymer of the present invention,preferred examples being also the same.

The mass-average molecular weight of the sixth polymer of the presentinvention is not particularly limited. However, the mass-averagemolecular weight of the sixth polymer of the present invention ispreferably 1,000 or more because the dry etching resistance is improvedat the above range, thereby bettering the form of the resist. Inaddition, it is preferably 100,000 or less because the solubility in aresist solution is improved at the above range, thereby bettering theresolution.

II. The Seventh Polymer of the Present Invention

The seventh polymer of the present invention comprises at least one ofconstitutional units represented by the formula (13) indicated below.The seventh polymer of the present invention may be a homopolymerconsisting of one type of the constitutional unit represented by thefollowing formula (13), a copolymer consisting of two or more types ofthe constitutional unit represented by the following formula (13), or acopolymer consisting of at least one type of the constitutional unitrepresented by the following formula (13) and at least one type ofconstitutional unit other than the constitutional unit represented bythe following formula (13). When the seventh polymer of the presentinvention is a copolymer, each constitutional unit can have any givensequence. Accordingly, this polymer may be a random copolymer, analternating copolymer, or a block copolymer. The proportion of theconstitutional unit represented by the following formula (13) in thepolymer is preferably 5 mol % or more.

In formula (13), W⁵ represents a direct bond or a methylene chaincontaining 1 to 6 carbon atoms [—(CH₂)_(x)— (wherein x represents aninteger of 0 to 6)], W⁶ represents a direct bond or a methylene chaincontaining 1 to 3 carbon atoms [—(CH₂)_(y)— (wherein y represents aninteger of 0 to 3)], W⁷ represents a methylene chain containing 1 to 3carbon atoms [—(CH₂)_(z)— (wherein z represents an integer of 1 to 3)],R²⁰ represents a hydrogen atom or a methyl group, each of R²¹ and R²²independently represents a hydrogen atom, a linear or branched alkylgroup containing 1 to 6 carbon atoms, a cyclic hydrocarbon groupcontaining 4 to 16 carbon atoms, or a linear or branched alkyl groupcontaining 1 to 6 carbon atoms which has a cyclic hydrocarbon groupcontaining 4 to 16 carbon atoms as a substituent; or R²¹ and R²²represent a cyclic hydrocarbon group containing 4 to 16 carbon atomstogether with the carbon atom to which they are bound. R²¹ and R²² maybe identical or may be different.

Herein, the methylene chain containing 1 to 6 carbon atoms may have, asa substituent, an alkyl group containing 1 to 3 carbon atoms which maybe optionally substituted, and may optionally have at least one etherbond therein. The methylene chain containing 1 to 3 carbon atoms mayhave a carbonyl group therein. Further, the alkyl group and the cyclichydrocarbon group may be unsubstituted, or may have at least onesubstituent selected from a group consisting of a linear or branchedalkyl group containing 1 to 6 carbon atoms which may be optionallysubstituted, a hydroxy group, a carboxy group, an acyl group containing2 to 6 carbon atoms, an alkoxy group containing 1 to 6 carbon atoms, anda carboxy group esterified with an alcohol containing 1 to 6 carbonatoms. When the alkyl group and the cyclic hydrocarbon group have two ormore substituents, the substituents may be of either a single type, ortwo or more types.

Examples of a substituent on the linear or branched alkyl groupcontaining 1 to 6 carbon atoms that is the substituent on the alkylgroup and the cyclic hydrocarbon group may include a hydroxy group, acarboxy group, an acyl group containing 1 to 6 carbon atoms, and anamino group. The number of substituents may be either one, or two ormore. When the above group has two or more substituents, thesubstituents may be of either a single type, or two or more types.

Examples of W⁵ in the above formula (13) may include a direct bond(which means that the oxygen atom and the carbon atom that are adjacentto W⁵ are directly bound to each other), CH₂, CH₂CH₂, CH₂CH₂CH₂,CH(CH₃)CH₂, CH₂O, CH₂CH₂O, CH₂CH(CH₃)O, CH(CH₃)CH₂O, —CH₂CH₂OCH₂CH₂O,CH₂CH(CH₃)OCH₂CH(CH₃)O, and CH(CH₃)CH₂OCH(CH₃)CH₂O.

Of these, in terms of storage stability of the polymer, a direct bond,CH₂, CH₂CH₂O and CH₂CH(CH₃)O are preferable as W⁵.

Examples of W⁶ in the above formula (13) may include a direct bond(which means that the oxygen atom and the carbon atom that are adjacentto W⁶ are directly bound to each other), CH₂, C(O), CH₂CH₂, CH₂C(O),CH₂CH₂CH₂, and CH₂C(O)CH₂.

Of these, in terms of storage stability of the polymer, a direct bond,CH₂, C(O) and CH₂C(O) are preferable as W⁶.

Examples of W⁷ in the above formula (13) may include CH₂, C(O), CH₂CH₂,CH₂C(O), CH₂CH₂CH₂, and CH₂C(O)CH₂.

Of these, in terms of storage stability of the polymer, CH₂, C(O) andCH₂C(O) are preferable as W⁷.

Examples of R²¹ and R²² in the above formula (13) may include a hydrogenatom, a methyl group, an ethyl group, a propyl group, an isopropylgroup, a butyl group, a tert-butyl group, a cyclopentyl group, acyclohexyl group, a cycloheptyl group, a 2-norbornyl group, a1-adamantyl group, a 1-adamantanemethyl group, a 1-adamantaneethylgroup, a 2-adamantyl group, a 2-adamantanemethyl group, a2-adamantaneethyl group and a 2-adamantanonyl group. Moreover, examplesof R²¹ and R²² may include a structure wherein these groups aresubstituted with at least one substituent selected from a groupconsisting of a linear or branched alkyl group containing 1 to 6 carbonatoms which may be optionally substituted (e.g., a hydroxy group, acarboxy group, a carboxy group esterified with an alcohol containing 1to 6 carbon atoms, an acyl group containing 1 to 6 carbon atoms, anamino group, and the like), a hydroxy group, a carboxy group, an acylgroup containing 2 to 6 carbon atoms, an alkoxy group containing 1 to 6carbon atoms, and a carboxy group esterified with an alcohol containing1 to 6 carbon atoms, or the like. The number of substituents may beeither one, or two or more. When the above group has two or moresubstituents, the substituents may be of either a single type, or two ormore types.

Further, R²¹ and R²² in the above formula (13) may form a cyclichydrocarbon structure containing 4 to 16 carbon atoms, together with thecarbon atom to which they are bound. Examples of such a cyclichydrocarbon structure may include an adamantylidene group, anorbornylidene group, and a cyclohexylidene group. Furthermore, examplesof such a cyclic hydrocarbon structure may also include those whereinthe cyclic hydrocarbon structure containing 4 to 16 carbon atoms issubstituted with at least one substituent selected from a groupconsisting of a linear or branched alkyl group containing 1 to 6 carbonatoms which may be optionally substituted (e.g., a hydroxy group, acarboxy group, a carboxy group esterified with an alcohol containing 1to 6 carbon atoms, an acyl group containing 1 to 6 carbon atoms, anamino group, and the like), a hydroxy group, a carboxy group, an acylgroup containing 2 to 6 carbon atoms, an alkoxy group containing 1 to 6carbon atoms, and a carboxy group esterified with an alcohol containing1 to 6 carbon atoms, or the like. The number of substituents may beeither one, or two or more. When the above structure has two or moresubstituents, the substituents may be of either a single type, or two ormore types.

As the constitutional unit represented by the above formula (13), aconstitutional unit wherein R²¹ represents a hydrogen atom, a methylgroup or an ethyl group and R²² represents a cyclopentyl group, acyclohexyl group or a cycloheptyl group, and a constitutional unitwherein R²¹ and R²² form a cyclic hydrocarbon group containing 5 to 12carbon atoms together with the carbon atom to which they are bound, arepreferable.

The seventh polymer of the present invention may comprise at least onetype of constitutional units other than the constitutional unitrepresented by the above formula (13). Examples of a monomer capable ofbeing copolymerized in the seventh polymer of the present invention mayinclude those that are conventionally known as a positive resist, anegative resist, an anti-reflection coat material or an insulatingfilm-forming material. For example, the monomer capable of beingcopolymerized may include a known monomer such as an acrylic acidderivative and a methacrylic acid derivative, which have a dry etchingresistance-improving group or a soluble group involving aciddissociation, a carboxylic acid (including a derivative thereof) havingan ethylene double bond causing alkali solubility, and known monomersused in the production of an acrylic resin. Specific examples of amonomer capable of being copolymerized may be the same as thosedescribed in the first polymer of the present invention.

As described in the first polymer of the present invention, the resinfor a chemically amplified resist composition is required to have both aproperty for becoming soluble in an alkaline aqueous solution by an acidso as to realize high sensitivity and a structure having high carbondensity so as to realize high dry etching resistance. The seventhpolymer of the present invention is excellent in solubility in anorganic solvent and heat resistance, and has little line edge roughness.When a structure having a property for becoming soluble in an alkalineaqueous solution by the action of an acid, or a structure having highdry etching resistance is introduced into such a polymer, an excellentresin for a chemically amplified resist composition can be obtained.

Examples of the structure having a functional group that is easilyeliminated by the action of an acid and the structure having high carbondensity may be the same as those described in the first polymer of thepresent invention.

In order to introduce the structure having a functional group that iseasily eliminated by the action of an acid or the structure having highcarbon density into the polymer, the monomer of the present inventionmay be copolymerized with a monomer having such a structure.

As a monomer having such a structure, for example, the one that is knownas a raw material monomer for a resin for a chemically amplified resistcomposition can be used. A raw material monomer used for the polymer ofthe present invention is arbitrarily selected depending on light sourceused in lithography.

For example, when a KrF excimer laser or an electron beam is used as alight source, considering its high etching resistance, a polymerobtained by copolymerizing the monomer of the present invention withp-hydroxystyrene or a derivative thereof is preferably used. In thiscase, the proportion of the constitutional unit derived from the monomerof the present invention in the polymer is preferably 5% or more and ispreferably 60% or less.

When an ArF excimer laser is used as a light source, a polymer obtainedby copolymerizing the monomer of the present invention with a monomerhaving a cyclic hydrocarbon group is preferably used. Copolymerizationwith a monomer having a cyclic hydrocarbon group enables high etchingresistance.

Among them, a polymer obtained by copolymerizing the monomer of thepresent invention, a monomer having a cyclic hydrocarbon group, amonomer having a hydrophilic functional group and/or a monomer having alactone structure is preferable.

As described in the first polymer of the present invention, it is knownthat an acrylic copolymer obtained by copolymerizing a monomer having acyclic hydrocarbon group and a monomer having a hydrophilic functionalgroup, or an acrylic copolymer obtained by copolymerizing a monomerhaving a cyclic hydrocarbon group and a monomer having a lactonestructure, is preferable as a resin for the ArF excimer laserlithography. Introduction of the monomer unit of the present inventioninto these polymers enables improvement of solubility in an organicsolvent and heat resistance without impairing the resist performancesuch as high sensitivity, high resolution or high dry etchingresistance, thereby providing an excellent resist pattern with only alittle line edge roughness.

A monomer unit having a cyclic hydrocarbon group imparts high dryetching resistance to a polymer comprising the same. In particular, amonomer unit having a protecting group that is eliminated by an acid (acyclic hydrocarbon group may also be a protecting group by itself)imparts also high sensitivity to the polymer comprising the same inphotolithography using an ArF excimer laser with a wavelength of 193 nm.The monomer units having a cyclic hydrocarbon group may be of either asingle type, or two or more types, if necessary.

Examples of the monomer unit having a cyclic hydrocarbon group may bethe same as those described in the first polymer of the presentinvention, preferred examples being also the same.

A monomer unit having a hydrophilic functional group imparts adhesion toa substrate to a polymer comprising the same. In particular, a monomerunit having a protecting group that is eliminated by an acid impartsalso high sensitivity to the polymer comprising the same inphotolithography using an ArF excimer laser with a wavelength of 193 nm.Examples of a hydrophilic functional group may include a terminalhydroxy group, an alkyl-substituted ether group, a δ-valerolactonylgroup, and a γ-butyrolactonyl group. It should be noted that some of theabove listed hydrophilic functional groups are generally included inhydrophobic groups. However, since even such functional groups havehydrophilicity that is needed in the present invention, they are hereindefined as a hydrophilic functional group. The monomer units having ahydrophilic functional group may be of either a single type, or two ormore types, if necessary.

Examples of the monomer unit having a hydrophilic functional group maybe the same as those described in the first polymer of the presentinvention, preferred examples being also the same.

A monomer unit having a lactone structure imparts high dry etchingresistance and adhesion to a substrate to a polymer comprising the same.The monomer units having a lactone structure may be of either a singletype, or two or more types, if necessary.

Examples of the monomer unit having a lactone structure may be the sameas those described in the first polymer of the present invention,preferred examples being also the same.

The mass-average molecular weight of the seventh polymer of the presentinvention is not particularly limited. However, the mass-averagemolecular weight of the seventh polymer of the present invention ispreferably 1,000 or more because the dry etching resistance is improvedat the above range, thereby bettering the form of the resist. Inaddition, it is preferably 100,000 or less because the solubility in aresist solution is improved at the above range, thereby bettering theresolution.

7. Method of Producing Polymer of the Present Invention

The polymer of the present invention (resin for a resist composition)can be produced by a known polymerization method. In terms of the simpleand easy production method, the polymer is preferably produced by theso-called drop polymerization method, in which a monomer solutionobtained by previously dissolving a monomer and a polymerizationinitiator in an organic solvent is added by drops into an organicsolvent that is maintained at a certain temperature.

The organic solvent used in the drop polymerization method is notparticularly limited. However, a solvent that can dissolve both amonomer and the obtained copolymer is preferable. Examples of such asolvent may include 1,4-dioxane, isopropyl alcohol, acetone,tetrahydrofuran and ethyl lactate. The use amount of an organic solventis not particularly limited, and it may be determined as appropriate.

The polymerization initiator used in the drop polymerization method isnot particularly limited. Examples of the polymerization initiator mayinclude an azo compound such as azobisisobutyronitrile or2,2′-azobis(2,4-dimethylvaleronitrile), and an organic peroxide such asbenzoyl peroxide. Moreover, a mercaptan such as n-butyl mercaptan,n-octyl mercaptan or 2-mercaptoethanol may be used as a chain transferagent. The use amount of a polymerization initiator and the use amountof a chain transfer agent are not particularly limited, and they may bedetermined as appropriate.

In the drop polymerization method, polymerization temperature is notparticularly limited, but in general, it is preferably within a range of50° C. to 150° C.

A polymer solution produced by the drop polymerization method is dilutedwith a good solvent such as tetrahydrofuran or 1,4-dioxane (a mixtureconsisting of two or more solvents may also be used) to a suitablesolution viscosity, if necessary. Then, the polymer solution is added bydrops into a large amount of poor solvent such as heptane, methanol orwater (a mixture consisting of two or more solvents may also be used),so as to deposit polymers. Thereafter, the obtained deposition isfiltered, and is fully dried, so as to obtain the polymer of the presentinvention.

The step of depositing polymers by dropping a polymer solution into alarge amount of poor solvent is called reprecipitation, and it isextremely effective to remove unreacted monomers, polymerizationinitiators and others that remain in the polymer solution. If theseunreacted monomers and others remain in the polymer solution, they arelikely to adversely affect the resist performance. Accordingly, it ispreferable to remove them, if possible. This reprecipitation process maybe omitted in some cases.

8. The Mixture of Polymers of the Present Invention

The above-described polymer of the present invention can be mixed withother polymers, if necessary. Mixed method is not particularly limited,and a known method can be used. The polymer of the present invention maybe used singly or in combination of two or more types. Moreover, otherpolymers that are mixed with the polymer of the present invention mayalso be used singly or in combination of two or more types.

The polymer of the present invention is preferably used as a materialfor a resist composition, and particularly as a material for achemically amplified resist composition. By using a polymer mixturecomprising the polymer of the present invention and other polymers, theexcellent performance as a resist composition, such as high solubilityin an organic solvent, improved line edge roughness or improved dryetching resistance, can be obtained, and at the same time, it becomespossible to control the properties within the optimum range.

The polymer to be mixed with the polymer of the present invention is notparticularly limited, but a polymer for a resist composition ispreferable. Examples of such a polymer may include those that areconventionally known as a positive resist, a negative resist, ananti-reflection coat material or an insulating film-forming material.For example, the polymer may include those obtained by (co)polymerizingmonomers such as an acrylic acid derivative and a methacrylic acidderivative, which have a dry etching resistance-improving group or asoluble group involving acid dissociation, a carboxylic acid (includinga derivative thereof) having an ethylene double bond causing alkalisolubility, and known monomers used in the production of an acrylicresin.

Examples of such an acrylic acid derivative may include an acryl esterin which the hydroxyl group of the carboxy group is protected with anacid-dissociating substituent, such as tert-butyl acrylate,tetrahydropyranyl acrylate, tetrahydrofuranyl acrylate,1-methylcyclohexyl acrylate, 1-methyladamantyl acrylate, ethoxyethylacrylate, ethoxypropyl acrylate, and the ester of acrylic acid and2-hydroxy-3-pinanone; or an acryl ester in which the hydroxyl group ofthe carboxy group is protected with an non-acid-dissociatingsubstituent, such as adamantyl acrylate, cyclohexyl acrylate, naphthylacrylate, benzyl acrylate, 3-oxocyclohexyl acrylate,bicyclo[2.2.1]heptyl acrylate, tricyclodecanyl acrylate, the ester ofacrylic acid and terpineol, and the ester of acrylic acid and3-bromoacetone.

Examples of such a methacrylic acid derivative may include methacrylicacid derivatives corresponding to the above listed acrylic acidderivatives.

In addition, examples of such a carboxylic acid having an ethylenedouble bond may include acrylic acid; methacrylic acid; maleic acid;fumaric acid; norbornene or a norbornene derivative having an alkylgroup, an alkyloxy group, a hydroxyl group, a hydroxyalkyl group, acarboxy group, an alkyloxycarbonyl group, or the like as a substituent;a vinyl ether derivative such as ethyl vinyl ether, cyclohexyl vinylether, and hydroxyethyl vinyl ether; a styrene derivative such asstyrene, p-hydroxystyrene, p-methoxystyrene, and p-tert-butoxystyrene;and maleic anhydride.

Examples of a known monomer used in the production of an acrylic resinmay include acrylic acid; methacrylic acid; or an acrylic acidderivative or an methacrylic acid derivative in which the hydrogen atomof these carboxylic acids is substituted with a group such as a methylgroup, an ethyl group, a n-propyl group, an isopropyl group, a n-butylgroup, a tert-butyl group, a n-hexyl group, an octyl group, a2-ethylhexyl group, a lauryl group, a 2-hydroxyethyl group, a2-hydroxypropyl group, a cyclopentyl group, a cyclohexyl group, a2-hydroxyethyl group, a norbornyl group, a tricyclodecanyl group, anadamantyl group, a 2-methyl-2-adamantyl group, a tetrahydropyranylgroup, a tetrahydrofuranyl group, or the like.

In addition to these acrylic resins, a polyhydroxystyrene resin, acycloolefin resin, and the like may also be mixed with the polymer ofthe present invention.

Among them, a polymer comprising at least one of constitutional unitsrepresented by the above formula (8), (9) or (10) is preferable as apolymer to be mixed with the polymer of the present invention. Thepolymer comprising at least one of constitutional units represented bythe above formula (8), (9) or (10) may be used singly or in combinationof two or more types.

The content (the total content) of the polymer of the present inventionin a polymer mixture is not particularly limited, but it is preferably1% or more by mass, more preferably 10% or more by mass, andparticularly preferably 20% or more by mass. Moreover, the content (thetotal content) of the polymer of the present invention in a polymermixture is preferably 99% or less by mass, more preferably 90% or lessby mass, and particularly preferably 80% or less by mass.

9. Resist Composition of the Present Invention

The resist composition of the present invention is obtained bydissolving the above-described polymer of the present invention and aphotoacid generator in a solvent. The polymer of the present inventionmay be used singly or in combination of two or more types. When theabove-described polymer mixture comprising the polymer of the presentinvention and a polymer other than those is used, the excellentperformance as a resist composition, such as high solubility in anorganic solvent, improved line edge roughness or improved dry etchingresistance, can be obtained, and at the same time, it becomes possibleto control the properties within the optimum range.

In terms of obtaining the sufficiently high effect of the presentinvention, the total content of the polymer of the present invention orthe polymer mixture of the present invention is preferably 1% or more bymass, and more preferably 5% or more by mass in a resist composition(including a solvent). Moreover, in terms of handling, the total contentof the polymer of the present invention or the polymer mixture of thepresent invention is preferably 80% or less by mass, and more preferably50% or less by mass in a resist composition (including a solvent).

A photoacid generator used for the resist composition of the presentinvention can appropriately be selected from among acid generators thatcan be used for a resist composition. The photoacid generator can beused singly or in combination of two or more types.

Examples of such a photoacid generator may include an onium saltcompound, a sulfone imide compound, a sulfone compound, a sulfonatecompound, a quinone diazide compound, and a diazo methane compound. Ofthese, onium salt compounds such as a sulfonium salt, iodonium salt,phosphonium salt, diazonium salt and pyridinium salt are preferablyused.

Specific examples of a photoacid generator may include triphenylsulfonium triflate, triphenyl sulfonium hexafluoro antimonate,triphenylsulfonium naphthalene sulfonate, (hydroxy phenyl)benzyl methylsulfonium toluene sulfonate, diphenyl iodonium triflate, diphenyliodonium pyrene sulfonate, diphenyl iodonium dodecyl benzene sulfonate,and diphenyl iodonium hexafluoro antimonate.

The use amount of a photoacid generator is appropriately determineddepending on the type of a photoacid generator used or other conditions,but in general, the amount is preferably within a range of 0.1 to 20parts by mass based on 100 parts by mass of a polymer for resist (thepolymer of the present invention or the polymer mixture of the presentinvention). By setting the use amount of a photoacid generator at 0.1part or more by mass based on 100 parts by mass of a polymer for resist,a chemical reaction due to the catalytic action of an acid generated asa result of exposure can sufficiently take place. Moreover, by settingthe use amount of a photoacid generator at 20 parts or less by massbased on 100 parts by mass of a polymer for resist, the stability of aresist composition is improved, and unevenness generated when thecomposition is applied, or scum or the like generated in a developingprocess is significantly reduced.

A solvent used for the resist composition of the present invention isarbitrarily selected depending on a purpose. However, the selection ofthe solvent may be subject to some constraints other than solubility ofa resin, such as the ones regarding the homogeneity and appearance of acoating film, and safety.

Examples of a solvent usually used in the present invention may includelinear ketones such as methyl ethyl ketone, 2-pentanone, and 2-hexanone;cyclic ketones such as cyclopentanone, and cyclohexanone; propyleneglycol monoalkyl acetates such as propylene glycol monomethyl etheracetate, and propylene glycol monoethyl ether acetate; ethylene glycolmonoalkyl ether acetates such as ethylene glycol monomethyl etheracetate, and ethylene glycol monoethyl ether acetate; propylene glycolmonoalkyl ethers such as propylene glycol monomethyl ether, andpropylene glycol monoethyl ether; ethylene glycol monoalkyl ethers suchas ethylene glycol monomethyl ether, ethylene glycol monoethyl ether,and ethylene glycol monoisopropyl ether; diethylene glycol alkyl etherssuch as diethylene glycol dimethyl ether, diethylene glycol monomethylether, and diethylene glycol diethyl ether; esters such as ethylacetate, and ethyl lactate; alcohols such as n-propyl alcohol, isopropylalcohol, n-butyl alcohol, tert-butyl alcohol, cyclohexanol, and1-octanol; 1,4-dioxane; ethylene carbonate; and γ-butyrolactone. Thesesolvents may be used singly or in combination of two or more types.

The use amount of a solvent is generally 200 parts or more by mass, andmore preferably 300 parts or more by mass based on 100 parts by mass ofa polymer for resist (the polymer of the present invention or thepolymer mixture of the present invention). Moreover, the use amount of asolvent is generally 5000 parts or less by mass, and more preferably2000 parts or less by mass based on 100 parts by mass of a polymer forresist (the polymer of the present invention or the polymer mixture ofthe present invention).

In addition, the resist composition of the present invention can furthercomprise various additives such as a surfactant, a quencher, asensitizer, an antihalation agent, a storage stabilizer or anantifoaming agent, if necessary. Any additives that are known in the artcan be used herein. The mixing amount of these additives is notparticularly limited, and it may be determined as appropriate.

10. Pattern Formation Method of the Present Invention

Next, an example of the pattern formation method of the presentinvention will be explained.

First, the resist composition of the present invention is coated byspin-coating or the like on the surface of a substrate to be processedsuch as a silicon wafer, on which a pattern is to be formed. Then, thesubstrate, on which the resist composition is coated, is dried by thebaking treatment (pre-bake), so that a resist film is formed on thesubstrate.

Next, a light with a wavelength of 250 nm or shorter, or an electronbeam, is applied to the thus obtained resist film using a photomask(exposure). The light used in the exposure is preferably a KrF excimerlaser or an ArF excimer laser, and particularly preferably an ArFexcimer laser.

After the light irradiation (exposure), the baking treatment (PEB) iscarried out as appropriate, and thereafter, the substrate is immersed inan alkaline developing solution, so as to eliminate the exposed portionby dissolving it therein (development). Any known alkaline developingsolution can be used herein. After the development, the substrate isrinsed with pure water or the like, as appropriate. Thus, a resistpattern is formed on the substrate to be processed.

In general, a substrate on which a resist pattern is formed isappropriately subjected to the baking treatment (post exposure bake) sothat the resist is reinforced. Portions having no resists areselectively etched. After the etching, the resist is generallyeliminated using a release agent.

11. Other Uses of the Polymer of the Present Invention I.Anti-Reflection Coat

The polymer of the present invention can also be used as ananti-reflection coat (cover film) material. In the pattern formationmethod, when a light source with a single and short wavelength is usedfor exposure, an incident light, a reflected light from aresist/substrate interface, and a re-reflected light from a resist/airinterface of the reflected light from the resist/substrate interface,interfere with one another in the resist film, and, as a result, thesubstantial exposure amount in the film changes, and it causes a problemthat the form of the resist pattern to be formed or the like is affected(phenomena of standing wave or multiple reflection). Consequently, theremay be a case where the line width of the resist pattern becomes unevenor a case where notching (local distortion) is generated. So as to solvesuch a problem, a process of forming an anti-reflection coat on a resistfilm is employed. The polymer of the present invention is preferablealso as an anti-reflection coat (cover film) material.

An anti-reflection coat composition, which is used for forming ananti-reflection coat, comprises the above-described polymer of thepresent invention and an organic solvent or water, and, if necessary, itfurther comprises a cross-linking agent, an acid generator or the like.The polymer of the present invention may be used singly or incombination of two or more types.

So as to increase solubility of a polymer compound in a solvent or toincrease adhesion, acrylic acid alkyl ester, acrylonitrile, maleicanhydride, maleimide, N-methylmaleimide, itaconic anhydride, vinylpyrrolidone, vinyl acetate, or the like may be copolymerized, andconstitutional units derived from these compounds may also be introducedinto the polymer of the present invention.

In terms of obtaining the sufficient effect by introduction of theconstitutional units, the proportion of the constitutional unit ispreferably 5 mol % or more, and particularly preferably 10 mol % or morein the polymer. In addition, in terms of obtaining the good film-formingproperty, the proportion of the constitutional unit is preferably 50 mol% or less, and particularly preferably 40 mol % or less in the polymer.

Furthermore, a constitutional unit having absorbance may be introducedinto the polymer of the present invention, so as to impart absorbance tothe polymer. Examples of a monomer copolymerized with the polymer of thepresent invention to introduce a constitutional unit having absorbancemay include a salicylate compound, a benzophenone compound, abenzotriazole compound, a cyanoacrylate compound, an azo compound, apolyene compound, an anthraquinone compound, a bisphenyl sulfonecompound, a bisphenyl sulfoxide compound, an anthracene compound, adiphenyl sulfone compound, a melamine compound, an urea compound, aguanamine compound, an acetoguanamine compound, a benzoguanaminecompound, a glycol uryl compound, a succinyl amide compound, and anethylene urea compound.

In terms of obtaining the sufficient effect by introduction of theconstitutional units having absorbance, the proportion of theconstitutional unit is preferably 5 mol % or more, and particularlypreferably 10 mol % or more in the polymer. In addition, in terms ofobtaining the good film-forming property, the proportion of theconstitutional unit having absorbance is preferably 50 mol % or less,and particularly preferably 40 mol % or less in the polymer.

Also, in addition to the polymer of the present invention, a resinhaving absorbance may be mixed, so as to impart absorbance to thepolymer composition. Examples of a resin having absorbance may include aresin binder comprising a quinolinyl group, a phenanthrenyl group, anacridinyl group or an alkylene anthryl group; a resin obtained bypolymerizing an epoxy resin with a dye having a substituent having ananthracene ring, a naphthalene ring or the like; a melamine resin; anurea resin; a benzoguanamine resin; and a glycol uryl resin.

In terms of obtaining the sufficient effect by mixing the above resins,the mixing amount of the resin is preferably 5 parts by mass or more,and particularly preferably 10 parts by mass or more based on 100 partsby mass of the total resins. In addition, in terms of obtaining the goodfilm-forming property, the mixing amount of the resin is preferably 50parts by mass or less, and particularly preferably 40 parts by mass orless based on 100 parts by mass of the total resins.

Furthermore, in addition to the polymer of the present invention,various water-soluble polymers such as a polyvinyl alcohol, apolyacrylic acid, a polymethacrylic acid, a polyvinyl pyrrolidone, apolyethylene oxide, an amylose, a dextran, a cellulose, a pullulan, anda functional fluorocarbon compound such as a perfluoroalkyl carboxylicacid polymer may be mixed, so as to improve film-forming property.

In terms of obtaining the sufficient effect by mixing the above resins,the mixing amount of the resin is preferably 5 parts by mass or more,and particularly preferably 10 parts by mass or more based on 100 partsby mass of the total resins. In addition, in terms of obtaining the goodadhesion to a substrate, the mixing amount of the resin is preferably 50parts by mass or less, and particularly preferably 40 parts by mass orless based on 100 parts by mass of the total resins.

No diffusion of a low molecular weight component into a resist layer isone of the properties required for an anti-reflection coat. Accordingly,there is generally applied a method in which thermal cross-linking isconducted by the bake after the spin coating of an anti-reflection coatcomposition. In this case, a cross-linking substituent is introducedinto the polymer to be used, and a cross-linking agent is added to theanti-reflection coat composition.

Examples of a cross-linking agent may include a melamine compound, aguanamine compound, a glycol uryl compound or an urea compound, whichhave at least one substituent selected from a group consisting of amethylol group, an alkoxymethyl group and an acyloxymethyl group, anepoxy compound, a thioepoxy compound, an isocyanate compound, an azidecompound, and a compound having a double bond such as an alkenyl ethergroup. In addition, these compounds may be used as an additive, but theymay also be introduced into the side chain of the polymer as a pendantgroup.

In terms of sufficient prevention of mixing with a resist, the mixingamount of a cross-linking agent is preferably 5 parts by mass or more,and particularly preferably 10 parts by mass or more based on 100 partsby mass of the total resins comprising the polymer of the presentinvention. In addition, in terms of sufficient prevention of decrease inantireflection effect and generation of crack of the film aftercross-linking, the mixing amount of a cross-linking agent is preferably50 parts by mass or less, and particularly preferably 40 parts by massor less based on 100 parts by mass of the total resins comprising thepolymer of the present invention.

And, so as to further promote a thermal cross-linking reaction, an acidgenerator may be added to the anti-reflection coat composition. Someacid generators generate acid by thermal decomposition, and othersgenerate acid by exposure to light. Any acid generator can be usedherein.

An organic solvent used in the anti-reflection coat composition is notparticularly limited, as long as a polymer, a cross-linking agent, anacid generator and other additives can be dissolved therein. Examples ofsuch an organic solvent may include ketones such as cyclohexanone andmethyl-2-amyl ketone; alcohols such as 3-methoxybutanol,3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, and1-ethoxy-2-propanol; ethers such as propylene glycol monomethyl ether,ethylene glycol monomethyl ether, propylene glycol monoethyl ether,ethylene glycol monoethyl ether, propylene glycol dimethyl ether, anddiethylene glycol dimethyl ether; and esters such as propylene glycolmonomethyl ether acetate, propylene glycol monoethyl ether acetate,ethyl lactate, ethyl pyruvate, butyl acetate, methyl3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate,tert-butyl propionate, propylene glycol monomethyl ether acetate, andpropylene glycol mono-tert-butyl ether acetate. These solvents may beused singly or in combination of two or more types.

In addition, a water-soluble organic solvent can be used with water.Examples of such a water-soluble organic solvent may include alcoholssuch as methylalcohol, ethylalcohol, and isopropylalcohol; ketones suchas acetone and methyl ethyl ketone; esters such as methyl acetate andethyl acetate; and polar solvent such as dimethylformamide,dimethylsulfoxide, methyl cellosolve, cellosolve, butyl cellosolve,cellosolve acetate, butyl carbitol, and carbitol acetate. These organicsolvents may be used singly or in combination of two or more types.

The mixing amount of a solvent is preferably 500 parts by mass or more,and more preferably 5,000 parts by mass or more based on 100 parts bymass of the total resins comprising the polymer of the presentinvention. In addition, the mixing amount of a solvent is preferably10,000 parts by mass or less, and more preferably 5,000 parts by mass orless based on 100 parts by mass of the total resins comprising thepolymer of the present invention.

Next, an example of the anti-reflection coat formation methods and anexample of the pattern formation methods will be explained.

First, the above-described anti-reflection coat composition is coated ona substrate by spin-coating using a spinner or the like. Then, thesubstrate, on which the anti-reflection coat composition is coated, issubjected to a heat treatment at a temperature within a range of 100° C.to 300° C., so that an anti-reflection coat with thickness within arange of 0.03 to 0.5 μm is formed. The heat treatment causes across-linking reaction of a resin component in the anti-reflection coatcomposition, and the anti-reflection coat to be formed becomes insolublein an alkaline solution.

After forming an anti-reflection coat as described above, a resistcomposition is coated thereon by spin-coating using a spinner or thelike, and then it is dried, so as to form a resist layer. Thereafter, aradiation such as a KrF excimer laser or an ArF excimer laser is appliedto the thus obtained resist layer through a desired mask pattern, forexample, by using a reduced projection exposure apparatus. After thelight irradiation, a heat treatment is carried out as appropriate, andthen, a development is carried out using a developing solution, forexample, an alkaline aqueous solution such as 1% to 10% by mass of atetramethylammonium hydroxide aqueous solution. If the resist is apositive type, the exposed portion is selectively dissolved andeliminated to form a photoresist pattern, which is faithful to the maskpattern. On the other hand, if the resist is a negative type, theunexposed portion is selectively dissolved and eliminated to form aphotoresist pattern, which is faithful to the mask pattern.

A resist to which the above-described anti-reflection coat compositioncomprising the polymer of the present invention is applied, is notparticularly limited, but a chemically amplified resist is preferable.Moreover, the anti-reflection coat may be formed either on a resistfilm, or under the resist film.

II. Radiation-Sensitive Composition

The polymer of the present invention can also be used as aradiation-sensitive composition, which is used for a negative resistsuch as a mask for the formation and lithography of a insulating film ofa liquid crystal display device, a semiconductor integrated circuitdevice, a magnetic head device, a solid-state image pickup device, anorganic EL device, and the like. The term “radiation” is used herein tomean an ultraviolet ray, a far ultraviolet ray, an X-ray, an electronbeam, a molecular beam, a γ-ray, a synchrotron radiation ray, a protonbeam, or the like.

A radiation-sensitive composition comprises the above-described polymerof the present invention, a radiation-sensitive acid generator, across-linking agent which cross-links by the action of an acid, and anorganic solvent or water, and, if necessary, it further comprises analkali-soluble resin or the like. The polymer of the present inventionmay be used singly or in combination of two or more types.

In this case, in terms of the high heat resistance, the mass-averagemolecular weight of the polymer of the present invention is preferably1000 or more, more preferably 2000 or more, and particularly preferably3000 or more. In addition, in terms of the fast developing rate, themass-average molecular weight of the polymer of the present invention ispreferably 100000 or less, more preferably 40000 or less, andparticularly preferably 30000 or less.

A radiation-sensitive acid generator is not particularly limited, aslong as the dissolution rate of the polymer of the present invention inan alkaline aqueous solution increases by an acid generated therefrom.Examples of such a radiation-sensitive acid generator may include thephotoacid generators used in the above-described resist composition ofthe present invention, and known acid generators such as an onium salt,a halogen-containing compound, a diazoketone compound, a diazomethanecompound, a sulfone compound, a sulfonate compound and a sulfoneimidecompound. These radiation-sensitive acid generators may be used singlyor in combination of two or more types.

In terms of forming a good pattern, the additive amount of aradiation-sensitive acid generator is preferably 0.01 part by mass ormore, and more preferably 0.1 part by mass or more based on 100 parts bymass of the polymer. Moreover, in terms of maintaining sufficientaffinity for a developing solution and preventing generation ofdefective development or the like, the additive amount of aradiation-sensitive acid generator is preferably 50 parts by mass orless, and more preferably 10 parts by mass or less based on 100 parts bymass of the polymer.

Examples of a cross-linking agent which cross-links by the action of anacid may include a bisphenol A-based epoxy compound, a bisphenol F-basedepoxy compound, a bisphenol S-based epoxy compound, a novolacresin-based epoxy compound, a resol resin-based epoxy compound, apoly(hydroxystyrene)-based epoxy compound, a methylol group-containingmelamine compound, a methylol group-containing benzoguanamine compound,a methylol group-containing urea compound, a methylol group-containingphenol compound, an alkoxyalkyl group-containing melamine compound, analkoxyalkyl group-containing benzoguanamine compound, an alkoxyalkylgroup-containing urea compound, an alkoxyalkyl group-containing phenolcompound, a carboxymethyl group-containing melamine resin, acarboxymethyl group-containing benzoguanamine resin, a carboxymethylgroup-containing urea resin, a carboxymethyl group-containing phenolresin, a carboxymethyl group-containing melamine compound, acarboxymethyl group-containing benzoguanamine compound, a carboxymethylgroup-containing urea compound, and a carboxymethyl group-containingphenol compound. Such a cross-linking agent may be used singly or incombination of two or more types.

In terms of prevention of decrease in residual ratio of the film,distortion or swelling of a pattern, and the like, the introductionratio of a cross-linking functional group is preferably 5 mol % or more,more preferably 10 mol % or more, and particularly preferably 15 mol %or more based on the total acid functional groups of the polymer of thepresent invention that are generated by a radiation-sensitive acidgenerator. Moreover, in terms of obtaining the good development propertyof the exposed portion, the introduction ratio of a cross-linkingfunctional group is preferably 60 mol % or less, more preferably 50 mol% or less, and particularly preferably 40 mol % or less based on thetotal acid functional groups of the polymer of the present inventionthat are generated by a radiation-sensitive acid generator.

Examples of an organic solvent used for the radiation-sensitivecomposition may include esters such as ethyl acetate, butyl acetate,amyl acetate, ethyl propionate, methyl butyrate, methyl benzoate, methyllactate, ethyl lactate, ethyl pyruvate, methyl β-isobutyrate, methyl3-methoxypropionate, ethyl 3-ethoxypropionate, and γ-butyrolactone;cellosolves such as methyl cellosolve, ethyl cellosolve, and butylcellosolve; cellosolve esters such as methyl cellosolve acetate, ethylcellosolve acetate, and butyl cellosolve acetate; propylene glycolesters such as propylene glycol monomethyl ether acetate and propyleneglycol monoethyl ether acetate; ethers such as 1,2-dimethoxyethane,1,2-diethoxyethane, tetrahydrofuran, and anisole; ketones such as methylethyl ketone, methyl isobutyl ketone, methyl n-amyl ketone,cyclohexanone, and isophorone; aprotic polar solvent such asdimethylformamide, dimethylacetoamide, N-methylpyrrolidone, dimethylsulfoxide, sulfolane; alcohols such as methanol and ethanol; andaromatic hydrocarbons such as toluene and xylene. These solvents may beused singly or in combination of two or more types.

To the radiation-sensitive composition, an alkali-soluble resin mayfurther be added. Examples of such an alkali-soluble resin may include anovolac resin, a hydrogenated novolac resin, an acetone-pyrogallolresin, a poly-o-hydroxystyrene, a poly-m-hydroxystyrene, apoly-p-hydroxystyrene, a hydrogenated polyhydroxystyrene, a halogen- oralkyl-substituted polyhydroxystyrene, a hydroxystyrene-N-substitutedmaleimide copolymer, an o/p- and m/p-hydroxystyrene copolymer, astyrene-maleic anhydride copolymer, a styrene-hydroxystyrene copolymer,an α-methylstyrene-hydroxystyrene copolymer, a carboxyl group-containingmethacrylic resin, and derivatives thereof. These alkali-soluble resinsmay be used singly or in combination of two or more types.

In terms of obtaining the sufficient effects that a pattern becomessharper during the development, or the like, the additive amount of analkali-soluble resin is preferably 5 mol % or more, and particularlypreferably 10 mol % or more. Moreover, in terms of stability of themixture, it is preferably 50 mol % or less, and particularly preferably40 mol % or less.

An additive such as a surfactant, a sensitizer, a stabilizer, anantifoaming agent or an acid-diffusion inhibitor can be mixed in theradiation-sensitive composition, if necessary.

The total solid content of the radiation-sensitive composition ispreferably 5% by mass or more, and more preferably 10% by mass or more.Moreover, the total solid content of the radiation-sensitive compositionis preferably 50% by mass or less, and more preferably 40% by mass orless.

The radiation-sensitive composition is prepared by uniformly dissolvingthe polymer of the present invention, and the like in a solvent so thatthe total solid content is within the above range, and then filtratingthe obtained solution using, for example, a filter with a pore size ofapproximately 0.2 μm.

Next, an example of methods of forming an insulating film using theradiation-sensitive resin composition comprising the polymer of thepresent invention will be explained.

First, the above-described radiation-sensitive resin composition iscoated on the surface of a substrate. Examples of a coating method mayinclude a spray coating method, a roll coating method, a spin coatingmethod, and a bar coating method. Then, the solvent is removed bypre-bake, so that a coating film is formed on the substrate. Theconditions for pre-bake vary according to the type and the content ofeach component, and the like, but in general, the preferable conditionsare that the treating temperature is within a range of 70° C. to 90° C.and the treating time is within a range of 1 to 15 minutes.

Thereafter, a radiation such as an ultraviolet ray is applied to thethus obtained coating film through a predetermined pattern mask. Afterthe irradiation, a development is carried out using a developingsolution so as to eliminate the unnecessary portion, so that apredetermined pattern is formed. Any development methods, including aliquid-putting method, a dipping method and a shower method, may beemployed. The developing time is generally within a range of 30 to 180seconds.

As a developing solution, an alkaline aqueous solution such as anaqueous solution of an inorganic alkali such as sodium hydroxide,potassium hydroxide, sodium carbonate, sodium silicate, sodiummetasilicate, and ammonia; an aqueous solution of a primary amine suchas ethylamine and n-propylamine; an aqueous solution of a secondaryamine such as diethylamine and di-n-propylamine; an aqueous solution ofa tertiary amine such as trimethylamine, methyldiethylamine,dimethylethylamine, and triethylamine; an aqueous solution of a tertiaryamine such as dimethylethanolamine, methyldiethanolamine, andtriethanolamine; an aqueous solution of a tertiary amine such aspyrrole, piperidine, N-methylpiperidine, N-methylpyrrolidine,1,8-diazabicyclo[5.4.0]-7-undecene, and1,5-diazabicyclo[4.3.0]-5-nonene; an aqueous solution of an aromatictertiary amine such as pyridine, collidine, lutidine, and quinoline; andan aqueous solution of a quaternary ammonium salt such astetramethylammonium hydroxide and tetraethylammonium hydroxide can beused. Moreover, an aqueous solution obtained by adding an appropriateamount of a water-soluble organic solvent such as methanol or ethanol,and a surfactant to the above alkaline aqueous solution, can also beused as a developing solution.

After the development, the unnecessary portion is eliminated by washingwith running water for 30 to 90 seconds, followed by air-drying withcompressed air or compressed nitrogen, to form a pattern. A radiationsuch as an ultraviolet ray is applied to the thus formed pattern, andthereafter, a heat treatment is carried out, using a heating apparatussuch as a hot plate or an oven, at a predetermined temperature, forexample, within a range of 180° C. to 250° C., for a predetermined time,for example, for 5 to 60 minutes on a hot plate, or for 30 to 90 minutesin an oven, so that an insulating film of interest can be obtained.

EXAMPLES

Next, the present invention will be explained further in detail by thefollowing examples. However, the examples are not intended to limit thescope of the present invention.

The term “part” is herein used to mean “part by mass”, unless otherwisespecified.

The measurement of properties of the produced copolymer was carried outby the following methods.

<Mass-Average Molecular Weight>

The mass-average molecular weight of the copolymer was determined by gelpermeation chromatography (hereinafter referred to as GPC) and expressedin terms of polystyrene standards. Chloroform or tetrahydrofuran wasused as a solvent.

<Average Copolymerization Composition of Copolymers (mol %)>

The average copolymerization composition of copolymers was determined by¹H-NMR measurement. Deuterated Chloroform, deuterated dimethylsulfoxide, or deuterated acetone was used as a solvent.

<Production of Monomers>

Example 1

25.0 g (0.1 mol) of 2,5-dimethyl-2-(1-adamantyl)-1,3-dioxolan-4-one,19.6 g (0.11 mol) of N-bromosuccinimide and 240 g of heptane were placedin a 500 ml egg-plant type flask equipped with a reflux condenser, andwhile the mixture was in a slurry state, the temperature was increasedto the reaction temperature, 60° C. under stirring.

When the mixture was stirred at 60° C. for about 2 hours, the reactionsolution became brown. When the reaction solution was further stirredfor 2 hours, it became transparent. After the reaction solution wascooled in an ice bath, it was filtered to remove succinimide, and then,the solvent was removed. The obtained transparent liquid was purifiedwith a column, so as to obtain 28.6 g of5-bromo-2,5-dimethyl-2-(1-adamantyl)-1,3-dioxolan-4-one (Formula (18),yield: 87%).

Elementary analysis: C 54.56%, H 6.64%, N 0%, O 14.73% (Theoreticalvalue: C 54.72%, H 6.43%, N 0%, O 14.58%)

Bromine content (by flask combustion/ion chromatography): 24.2%(Theoretical value: 24.27%)

¹H-NMR (270 MHz, Internal standard: CDCl₃, δppm): 1.40 to 1.72 (m,adamantyl group), 1.73 (s, 3H), 2.20 (s, 3H)

Infrared absorption spectrum (KBr tablet, cm⁻¹): 2908, 2851, 1809, 1452,1385, 1282, 1223, 1195, 1167, 1063, 943, 928

16.5 g (0.05 mol) of the obtained5-bromo-2,5-dimethyl-2-(1-adamantyl)-1,3-dioxolan-4-one was placed in a100 ml egg-plant type flask, and 73.1 g (1.0 mol) ofN,N-dimethylformamide was added thereto, followed by intensivelystirring at 40° C. for 2 hours. After completion of the stirring, themixture was transferred into a 500 ml separatory funnel, and 200 g ofisopropyl ether was added thereto, followed by fully shaking.Thereafter, the obtained mixture was left at rest, so as to separate themixture into two layers. And then, the N,N-dimethylformamide phase thatwas a lower layer was removed. The isopropyl ether phase that was aupper layer washed with water to remove N,N-dimethylformamide dissolvedtherein. Thereafter, isopropyl ether was removed, so as to obtain whitecrystals. The obtained white crystals were recrystallized from hexane,so as to obtain 10.9 g of5-methylene-2-(1-adamantyl)-2-methyl-1,3-dioxolan-4-one at a purity of99.8% (Formula (19), yield: 88%).

Elementary analysis: C 70.40%, H 8.14%, N 0%, O 19.38% (Theoreticalvalue: C 72.55%, H 8.12%, N 0%, O 19.33%)

The ¹H-NMR spectrum (270 MHz, Internal standard: CDCl₃) of the compoundof formula (19) is shown in FIG. 1, and the ¹³C-NMR spectrum (270 MHz,Internal standard: CDCl₃) of the same compound is shown in FIG. 2.

Example 2

22.2 g (0.1 mol) ofspiro[adamantan-2,2′-(5′-methyl-1′,3′-dioxolan-4′-one)], 21.4 g (0.12mol) of N-bromosuccinimide and 200 g of cyclohexane were placed in a 500ml egg-plant type flask equipped with a reflux condenser, and while themixture was in a slurry state, the temperature was increased to thereaction temperature, 60° C. under stirring.

When the mixture was stirred at 60° C. for about 2 hours, the reactionsolution became brown. When the reaction solution was further stirredfor 2 hours, it became transparent. After the reaction solution wascooled in an ice bath, it was filtered to remove succinimide, and then,the solvent was removed. The deposited crystals were recrystallized fromhexane, so as to obtain 25.6 g ofspiro[adamantan-2,2′-(5′-bromo-5′-methyl-1′,3′-dioxolan-4′-one)](Formula (20), yield: 85%).

Elementary analysis: C 51.70%, H 5.82%, N 0%, O 16.19% (Theoreticalvalue: C 51.84%, H 5.69%, N 0%, O 15.94%)

Bromine content (by flask combustion/ion chromatography): 26.4%(Theoretical value: 26.53%)

¹H-NMR (270 MHz, Internal standard: CDCl₃, δppm): 1.66 to 2.07 (m,adamantyl group), 2.20 (s, 3H)

Infrared absorption spectrum (KBr tablet, cm⁻¹): 2917, 2860, 1804, 1455,1388, 1290, 1179, 1111, 1091, 1065, 1022, 988, 929

15.1 g (0.05 mol) of the obtainedspiro[adamantan-2,2′-(5′-bromo-5′-methyl-1′,3′-dioxolan-4′-one)] wasplaced in a 500 ml egg-plant type flask, and 200 g of cyclohexane wasadded thereto and dissolved therein. Thereafter, 36.5 g (0.5 mol) ofN,N-dimethylformamide was added thereto, followed by intensivelystirring at room temperature for 2 hours. After completion of thestirring, the mixture was transferred into a 500 ml separatory funneland was left at rest, so as to separate the mixture into two layers. Andthen, the lower N,N-dimethylformamide layer was removed. The uppercyclohexane layer washed with water to remove N,N-dimethylformamidedissolved therein. Thereafter, cyclohexane was removed, so as to obtainwhite crystals. The obtained white crystals were recrystallized fromhexane, so as to obtain 9.3 g ofspiro[adamantan-2,2′-(5′-methylene-1′,3′-dioxolan-4′-one)] at a purityof 99.6% (Formula (21), yield: 85%).

Elementary analysis: C 70.69%, H 7.35%, N 0%, O 21.84% (Theoreticalvalue: C 70.89%, H 7.32%, N 0%, O 21.79%)

The ¹H-NMR spectrum (270 MHz, Internal standard: CDCl₃) of the compoundof formula (21) is shown in FIG. 3, and the ¹³C-NMR spectrum (270 MHz,Internal standard: CDCl₃) of the same compound is shown in FIG. 4.

Example 3

18.2 g (0.1 mol) ofspiro[norbornan-2,2′-(5′-methyl-1′,3′-dioxolan-4′-one)], 19.6 g (0.11mol) of N-bromosuccinimide and 280 g of cyclohexane were placed in a 500ml egg-plant type flask equipped with a reflux condenser, and while themixture was in a slurry state, the temperature was increased to thereaction temperature, 60° C. under stirring.

When the mixture was stirred at 60° C. for about 2 hours, the reactionsolution became brown. When the reaction solution was further stirredfor 2 hours, it became transparent. After the reaction solution wascooled in an ice bath, it was analyzed. As a result, it was found that25.1 g ofspiro[norbornan-2,2′-(5′-bromo-5′-methyl-1′,3′-dioxolan-4′-one)] wascontained in the reaction solution (Formula (22), yield: 96%).

The obtained reaction solution was transferred into a 500 ml egg-planttype flask, and 73.0 g (1.0 mol) of N,N-dimethylformamide was addedthereto, followed by intensively stirring at room temperature for 2hours. Succinimide generated as a by-product in the previous step wasdissolved in N,N-dimethylformamide during the stirring. After completionof the stirring, insoluble products were removed from the reactionsolution by filtration, and the obtained filtrate was transferred into a500 ml separatory funnel. The solution was left at rest, so as toseparate it into two layers. And then, the lower N,N-dimethylformamidelayer was removed. The upper cyclohexane layer washed with water toremove N,N-dimethylformamide dissolved therein. Thereafter, cyclohexanewas removed, so as to obtain white crystals. The obtained white crystalswere recrystallized from hexane, so as to obtain 15.5 g ofspiro[norbornan-2,2′-(5′-methylene-11,3′-dioxolan-4′-one)] at a purityof 99.5% (Formula (23), yield: 86%).

Elementary analysis: C 66.39%, H 6.84%, N 0%, O 27.03% (Theoreticalvalue: C 66.65%, H 6.71%, N 0%, O 26.64%)

The ¹H-NMR spectrum (270 MHz, Internal standard: CDCl₃) of the compoundof formula (23) is shown in FIG. 5, and the ¹³C-NMR spectrum (270 MHz,Internal standard: CDCl₃) of the same compound is shown in FIG. 6.

Example 4

A mixture obtained by dissolving 16.4 g (0.05 mol) of5-bromomethyl-2-(1-adamantyl)-2-methyl-1,3-dioxolan-4-one in 58 g ofisopropyl ether was placed in a flask equipped with an agitator, athermometer, a condenser and a dropping funnel. 36.5 g (0.5 mol) ofN,N-dimethylformamide was added by drops thereto, followed byintensively stirring at room temperature for 4 hours. After completionof the stirring, insoluble products were removed from the reactionsolution by filtration, and the obtained filtrate was transferred into a500 ml separatory funnel. The solution was left at rest, so as toseparate it into two layers, and the lower N,N-dimethylformamide layerwas removed. The upper isopropyl ether layer washed with water to removeN,N-dimethylformamide dissolved therein. Thereafter, isopropyl ether wasremoved, so as to obtain white crystals. The obtained white crystalswere recrystallized from hexane, so as to obtain 6.6 g of5-methylene-2-(1-adamantyl)-2-methyl-1,3-dioxolan-4-one (hereinafterreferred to as AdMDO) (yield: 53%).

Comparative Example 1

25.0 g (0.1 mol) of 2,5-dimethyl-2-(1-adamantyl)-1,3-dioxolan-4-one,19.6 g (0.11 mol) of N-bromosuccinimide and 240 g of heptane were placedin a 500 ml egg-plant type flask equipped with a reflux condenser, andwhile the mixture was in a slurry state, the temperature was increasedto the reaction temperature, 80° C. under stirring.

When the mixture was stirred at 80° C. for about 1 hour, the reactionsolution became brown. As a result of analyzing the reaction solutionimmediately before it became brown, it was found that the reactionsolution contained5-bromo-2,5-dimethyl-2-(1-adamantyl)-1,3-dioxolan-4-one corresponding to3% of the raw materials and adamantyl methyl ketone corresponding to 4%of the raw materials. When the reaction solution was further stirred for2 hours, it became transparent. After the reaction solution was cooledin an ice bath, it was filtered to remove succinimide. As a result ofanalyzing the reaction solution, it was found that the reaction solutioncontained only 3.6 g of5-bromo-2,5-dimethyl-2-(1-adamantyl)-1,3-dioxolan-4-one (yield: 11%) andthat 82% of the raw materials was decomposed into adamantyl methylketone.

Comparative Example 2

22.2 g (0.1 mol) ofspiro[adamantan-2,2′-(5′-methyl-1′,3′-dioxolan-4′-one)], 21.4 g (0.12mol) of N-bromosuccinimide and 200 g of cyclohexane were placed in a 500ml egg-plant type flask equipped with a reflux condenser, and while themixture was in a slurry state, the temperature was increased to thereaction temperature, 80° C. under stirring.

When the mixture was stirred at 80° C. for about 1 hour, the reactionsolution became brown. As a result of analyzing the reaction solutionimmediately before it became brown, it was found that the reactionsolution containedspiro[adamantan-2,2′-(5′-bromo-5′-methyl-1′,3′-dioxolan-4′-one)]corresponding to 2% of the raw materials and 2-adamantanonecorresponding to 6% of the raw materials. When the reaction solution wasfurther stirred for 2 hours, it became transparent. After the reactionsolution was cooled in an ice bath, it was filtered to removesuccinimide. As a result of analyzing the reaction solution, it wasfound that the reaction solution contained only 2.4 g ofspiro[adamantan-2,2′-(5′-bromo-5′-methyl-1′,3′-dioxolan-4′-one)] (yield:8%) and that 85% of the raw materials was decomposed into2-adamantanone.

Comparative Example 3

18.2 g (0.1 mol) ofspiro[norbornan-2,2′-(5′-methyl-1′,3′-dioxolan-4′-one)], 19.6 g (0.11mol) of N-bromosuccinimide and 280 g of cyclohexane were placed in a 500ml egg-plant type flask equipped with a reflux condenser, and while themixture was in a slurry state, the temperature was increased to thereaction temperature, 80° C. under stirring.

When the mixture was stirred at 80° C. for about 1 hour, the reactionsolution became brown. As a result of analyzing the reaction solutionimmediately before it became brown, it was found that the reactionsolution containedspiro[norbornan-2,2′-(5′-bromo-5′-methyl-1′,3′-dioxolan-4′-one)]corresponding to 5% of the raw materials and 2-norbornanonecorresponding to 6% of the raw materials. When the reaction solution wasfurther stirred for 2 hours, it became transparent. After the reactionsolution was cooled in an ice bath, it was filtered to removesuccinimide. As a result of analyzing the reaction solution, it wasfound that the reaction solution contained only 3.4 g ofspiro[norbornan-2,2′-(5′-bromo-5′-methyl-1′,3′-dioxolan-4′-one)] (yield:13%) and that 82% of the raw materials was decomposed into2-norbornanone.

Comparative Example 4

18.2 g (0.1 mol) ofspiro[norbornan-2,2′-(5′-methyl-1′,3′-dioxolan-4′-one)], 19.6 g (0.11mol) of N-bromosuccinimide and 280 g of cyclohexane were placed in a 500ml egg-plant type flask equipped with a reflux condenser, and while themixture was in a slurry state, the temperature was increased to thereaction temperature, 45° C. under stirring.

When the mixture was stirred at 45° C. for about 6 hours, no change inthe color of the reaction solution was observed. After the reactionsolution was cooled in an ice bath, it was filtered to removeN-bromosuccinimide. As a result of analyzing the reaction solution, itwas found that the reaction solution contained nospiro[norbornan-2,2′-(5′-bromo-5′-methyl-1′,3′-dioxolan-4′-one)] andthat most of spiro[norbornan-2,2′-(5′-methyl-1′,3′-dioxolan-4′-one)] asa raw material was unreacted.

Comparative Example 5

16.5 g (0.05 mol) of5-bromo-2,5-dimethyl-2-(1-adamantyl)-1,3-dioxolan-4-one was placed in a500 ml egg-plant type flask, and 200 g of isopropyl ether was addedthereto and dissolved therein. While cooling with a refrigerant of −10°C., 9.1 g (0.06 mol) of 1,8-diazabicyclo[5.4.0]-7-undecene diluted with20 g of isopropyl ether was added by drops into the solution over 1hour, followed by stirring at room temperature for 2 hours. Aftercompletion of the stirring, the reaction solution was analyzed. As aresult, it was found that the reaction solution contained only 1.7 g of5-methylene-2-(1-adamantyl)-2-methyl-1,3-dioxolan-4-one (yield: 14%) andthat 80% of the raw materials was decomposed into adamantyl methylketone.

Comparative Example 6

15.0 g (0.05 mol) ofspiro[adamantan-2,2′-(5′-bromo-5′-methyl-1′,3′-dioxolan-4′-one)] wasplaced in a 500 ml egg-plant type flask, and 200 g of cyclohexane wasadded thereto and dissolved therein. While cooling in an ice bath, 6.1 g(0.06 mol) of triethylamine diluted with 20 g of cyclohexane was addedby drops into the solution over 1 hour, followed by stirring at roomtemperature for 2 hours. After completion of the stirring, the reactionsolution was analyzed. As a result, it was found that the reactionsolution contained only 1.2 g ofspiro[adamantan-2,2′-(5′-methylene-1′,3′-dioxolan-4′-one)] (yield: 11%)and that 83% of the raw materials was decomposed into 2-adamantanone.

Comparative Example 7

13.1 g (0.05 mol) ofspiro[norbornan-2,2′-(5′-bromo-5′-methyl-1′,3′-dioxolan-4′-one)] wasplaced in a 500 ml egg-plant type flask, and 200 g of isopropyl etherwas added thereto and dissolved therein. While cooling with arefrigerant of −10° C., 6.1 g (0.06 mol) of triethylamine diluted with20 g of isopropyl ether was added by drops into the solution over 1hour, followed by stirring at room temperature for 2 hours. Aftercompletion of the stirring, the reaction solution was analyzed. As aresult, it was found that the reaction solution contained only 1.3 g ofspiro[norbornan-2,2′-(5′-methylene-1′,3′-dioxolan-4′-one)] (yield: 14%)and that 81% of the raw materials was decomposed into adamantanone

Comparative Example 8

A mixture obtained by dissolving 16.4 g of5-bromomethyl-2-(1-adamantyl)-2-methyl-1,3-dioxolan-4-one in 80 ml ofisopropyl ether was placed in a flask equipped with an agitator, athermometer, a condenser and a dropping funnel. While cooling in an icebath, 9.1 g (0.06 mol) of 1,8-diazabicyclo[5.4.0]-7-undecene dilutedwith 20 ml of isopropyl ether was added by drops into the solution over1 hour, followed by stirring at room temperature for 2 hours. Aftercompletion of the stirring, the reaction solution was analyzed. As aresult, it was found that the reaction solution contained only 1.8 g of5-methylene-2-(1-adamantyl)-2-methyl-1,3-dioxolan-4-one (yield: 15%) andthat 81% of the raw materials was decomposed into adamantyl methylketone.

<Production of Polymers>

Example 5

Production of the polymer represented by the following formula (24)

30.0 parts of ethyl lactate was placed in a separable flask equippedwith a nitrogen introduction port, an agitator, a condenser and athermometer, in a nitrogen atmosphere, and while stirring, thetemperature of a hot-water bath was raised to 80° C. A monomer solutionobtained by mixing 1.98 parts of AdMDO, 13.22 parts of2-methacryloyloxy-2-methyladamantane (hereinafter referred to as MAdMA),8.50 parts of β-methacryloyloxy-γ-butyrolactone (hereinafter referred toas HGBMA), 30.0 parts of ethyl lactate and 0.21 parts ofazobisisobutyronitrile, was added by drops into the flask at a certainrate over 6 hours, and then, the temperature of 80° C. was kept for 2hours. Thereafter, while stirring, the obtained reaction solution wasadded by drops into 800 parts of methanol, so as to obtain a whiteprecipitate. The obtained precipitate was filtered, and dried under areduced pressure at 60° C. for approximately 10 hours. Thereafter, theprecipitate was dissolved in 45 parts of tetrahydrofuran, and whilestirring, the obtained solution was added by drops into 800 parts ofmethanol. The obtained precipitate was filtered, and dried under areduced pressure at 60° C. for approximately 40 hours.

Subsequently, the properties of the obtained copolymer were measured.According to GPC analysis, mass-average molecular weight (hereinafterreferred to as Mw) was 7,200, molecular weight distribution (hereinafterreferred to as Mw/Mn) was 1.45, and copolymerization ratio was AdMDO:MAdMA: HGBMA=10:45:45 according to the integration ratio of ¹H-NMR.

Example 6 Production of the Polymer Represented by the Following Formula(25)

Synthesis was carried out in the same manner as in Example 5 with theexception that 1.98 parts of AdMDO was changed into 0.99 parts of thesame compound, 13.22 parts of MAdMA was changed into 14.01 parts of2-methacryloyloxy-2-ethyladamantane (hereinafter referred to as EAdMA),8.50 parts of HGBMA was changed into 11.80 parts of a mixture consistingof 7-methacryloyloxy-3-oxatricyclo[5.2.1.0^(2,6)]decan-2-one and8-methacryloyloxy-3-oxatricyclo[5.2.1.0^(2,6)]decan-2-one (hereinafterreferred to as OTDMA), so as to obtain a copolymer.

Subsequently, the properties of the obtained copolymer were measured.According to GPC analysis, Mw was 8,000, Mw/Mn was 1.43, andcopolymerization ratio was AdMDO: EAdMA: OTDMA=5:50:45 according to theintegration ratio of ¹H-NMR.

Example 7 Production of the Polymer Represented by the Following Formula(26)

Synthesis was carried out in the same manner as in Example 5 with theexception that 0.99 parts of AdMDO, 14.01 parts of EAdMA, 11.80 parts ofOTDMA and 1.26 parts of 4,4-dimethyl-2-methylene-4-butanolide(hereinafter referred to as DMMB) were copolymerized, so as to obtain acopolymer.

Subsequently, the properties of the obtained copolymer were measured.According to GPC analysis, Mw was 9,200, Mw/Mn was 1.51, andcopolymerization ratio was AdMDO: EAdMA: OTDMA: DMMB=5: 45:40:10according to the integration ratio of ¹H-NMR.

Example 8 Production of the Polymer Represented by the Following Formula(27)

Synthesis was carried out in the same manner as in Example 5 with theexception that 1.98 parts of AdMDO was changed into 1.44 parts of NrMDO,so as to obtain a copolymer.

Subsequently, the properties of the obtained copolymer were measured.According to GPC analysis, Mw was 7,600, Mw/Mn was 1.49, andcopolymerization ratio was NrMDO: MAdMA: HGBMA=10:45:45 according to theintegration ratio of ¹H-NMR.

Example 9 Production of the Polymer Represented by the Following Formula(28)

Synthesis was carried out in the same manner as in Example 5 with theexception that 1.98 parts of AdMDO was changed into 1.28 parts ofspiro[cyclohexan-2′-(5′-methylene-1′,3′-dioxolan-4′-one)] (hereinafterreferred to as CyMDO), so as to obtain a copolymer.

Subsequently, the properties of the obtained copolymer were measured.According to GPC analysis, Mw was 8,300, Mw/Mn was 1.55, andcopolymerization ratio was CyMDO: MAdMA: HGBMA=10:45:45 according to theintegration ratio of ¹H-NMR.

Comparative Example 9 Production of the Polymer Represented by theFollowing Formula (29)

Synthesis was carried out in the same manner as in Example 5 with theexception that 13.22 parts of MAdMA and 8.50 parts of HGBMA werecopolymerized, so as to obtain a copolymer.

Subsequently, the properties of the obtained copolymer were measured.According to GPC analysis, Mw was 7,400, Mw/Mn was 1.35, andcopolymerization ratio was MAdMA: HGBMA=50:50 according to theintegration ratio of ¹H-NMR.

Comparative Example 10 Production of the Polymer Represented by theFollowing Formula (30)

Synthesis was carried out in the same manner as in Example 5 with theexception that 14.01 parts of EAdMA and 11.80 parts of HGBMA werecopolymerized, so as to obtain a copolymer.

Subsequently, the properties of the obtained copolymer were measured.According to GPC analysis, Mw was 9,600, Mw/Mn was 1.41, andcopolymerization ratio was EAdMA: OTDMA=50:50 according to theintegration ratio of ¹H-NMR.

Comparative Example 11 Production of the Polymer Represented by theFollowing Formula (31)

Synthesis was carried out in the same manner as in Example 5 with theexception that 14.01 parts of EAdMA, 11.80 parts of OTDMA and 1.26 partsof DMMB were copolymerized, so as to obtain a copolymer.

Subsequently, the properties of the obtained copolymer were measured.According to GPC analysis, Mw was 10,500, Mw/Mn was 1.45, andcopolymerization ratio was EAdMA: OTDMA: DMMB=50:40:10 according to theintegration ratio of ¹H-NMR.

With regard to the polymers obtained in Examples 5 to 8 and Comparativeexamples 9 to 11, the solubility in a resist solvent, and thesensitivity, the resolution, the dry etching resistance (etching rate)and the line edge roughness of the obtained resist patterns weremeasured and evaluated as follows. The results are shown in Table 1.

<Solubility in a Resist Solvent>

Each copolymer was dissolved in a certain amount of resist solvent(propylene glycol monomethyl ether acetate) at room temperature whilestirring, so that the solid content became 20% by mass, and the timerequired for the copolymer to be completely dissolved was measured. Theresults are shown in Table 1.

Symbols in the table mean as follows:

⊚: The time required for the copolymer to be completely dissolved isless than 1 hour;

∘: The time required for the copolymer to be completely dissolved is 1hour or more, and less than 6 hours;

Δ: The time required for the copolymer to be completely dissolved is 6hours or more, and less than 24 hours;

x: The time required for the copolymer to be completely dissolved is 24hours or more, or the copolymer is insoluble.

<Formation of a Resist Pattern>

100 parts of each of the copolymers obtained in Examples 5 to 8 andComparative examples 9 to 11, and 2 parts of triphenylsulfonium triflatewere dissolved in 500 parts of propylene glycol monomethyl etheracetate, so as to obtain a homogeneous solution. Thereafter, thesolution was filtered with a fluorocarbon resin filter, so as to preparea resist composition solution. And then, each of the preparedcomposition solutions was spin-coated on a 3-inch silicon wafer, andusing a hot plate, pre-bake was carried out at 120° C. for 60 seconds toform a thin film having a film thickness of 0.5 μm. Subsequently, thethin film was exposed using a light exposure system with a wavelength of193 nm (SP193 manufactured by Nikon Corporation), and then, using a hotplate, baking was carried out at 120° C. for 60 seconds. Thereafter,development was carried out at room temperature using a 2.38% by masstetramethylammonium hydroxide aqueous solution, followed by washing withpure water and drying, so as to form a resist pattern.

The sensitivity, the resolution, the dry etching resistance (etchingrate) and the line edge roughness of each of the obtained resistpatterns were measured and evaluated as follows. The results are shownin Table 1.

<Sensitivity>

Sensitivity was defined as a light exposure (mJ/cm²), which forms aline-and-space pattern (line/space=1/1) at a line width of 1/1.

<Resolution>

Resolution was defined as the minimal dimension (μm) of a resistpattern, which was resolved when exposure was carried out at theabove-described light exposure.

<Etching Rate>

The resist film formed on a silicon wafer was subjected to a dry etchingtreatment using an etching machine manufactured by Tokyo Electron Ltd.The dry etching treatment was carried out using C₄F₈/Ar/O₂ mixed gas,under etching conditions at 2,000 W, at 50 mTorr, for 50 seconds. Thefilm thickness of the resist film was measured before and after the dryetching treatment, using a Lambda Ace VM-8000J light-interference typethickness measurement system manufactured by Dainippon Screen MFG Co.,Ltd. Etching rate of the resist was defined as the reduced amount of thefilm thickness per unit time. Moreover, the etching rate was normalizedby setting the etching rate of a novolac resin as 1.

<Line Edge Roughness>

The minimum line width of the line of the formed line-and-space pattern(line/space=1/1) was subtracted from the maximum line width thereof, andthe obtained value was divided by the half-value width of the maximumline width of the line. The thus obtained value was defined as line edgeroughness.

TABLE 1 Sensitivity Resolution Etching Line edge Solubility in (mJ/cm²)(μm) rate roughness resist solvent Polymer of 5.0 0.18 1.03 0.05 ⊚Example 5 Polymer of 4.9 0.17 1.02 0.07 ◯ Example 6 Polymer of 4.9 0.171.03 0.07 ◯ Example 7 Polymer of 5.0 0.18 1.04 0.10 ◯ Example 8 Polymerof 5.0 0.18 1.06 0.10 ⊚ Example 9 Polymer of 5.0 0.18 1.05 0.14 ΔComparative example 9 Polymer of 4.9 0.19 1.03 0.13 X Comparativeexample 10 Polymer of 4.9 0.18 1.05 0.13 X Comparative example 11

The polymers of the present invention (Examples 5 to 8) were moreexcellent in solubility in a resist solvent than the polymers ofComparative examples 9 to 11. Moreover, the chemically amplified resistcompositions comprising the polymers of the present invention (Examples5 to 8) had sufficient sensitivity, resolution and etching resistance,and at the same time, the chemically amplified resist compositions hadless line edge roughness than that of the chemically amplified resistcompositions comprising the polymers of Comparative examples 9 to 11.

Example 10 Synthesis of the Polymer P-1 Represented by the FollowingFormula (32)

15.8 parts of propylene glycol monomethyl ethyl acetate (hereinafterreferred to as PGMEA) and 4.0 parts of γ-butyrolactone (hereinafterreferred to as γBL) were placed in a separable flask equipped with anitrogen introduction port, an agitator, a condenser and a thermometer,in a nitrogen atmosphere, and while stirring, the temperature of ahot-water bath was raised to 80° C. A monomer solution obtained bymixing 10.0 parts of2-exo-methacryloyloxy-4-oxatricyclo[4.2.1.0^(3,7)]nonan-5-one(hereinafter referred to as OTNMA), 10.5 parts of2-methacryloyloxy-2-methyladamantane (hereinafter referred to as MAdMA),3.2 parts of5-methacryloyloxy-2-methyl-2-(1-adamantyl)-1,3-dioxolan-4-one(hereinafter referred to as M-1 monomer), 35.6 parts of PGMEA and 0.82parts of azobisisobutyronitrile, was added by drops into the flask at acertain rate over 7 hours, and then, the temperature of 80° C. was keptfor 2 hours. Thereafter, while stirring, the obtained reaction solutionwas added by drops into 800 parts of methanol, so as to obtain a whiteprecipitate (polymer P-1). The obtained precipitate was filtered, anddried under a reduced pressure at 60° C. for approximately 10 hours.Thereafter, the dried precipitate was dissolved in 45 parts oftetrahydrofuran, and while stirring, the obtained solution was added bydrops into 800 parts of methanol. The obtained precipitate was filtered,and dried under a reduced pressure at 60° C. for approximately 40 hours.

The properties of the obtained polymer were measured, and the resultsare shown in Table 2.

Example 11 Synthesis of the Polymers P-2 to P-7

The polymers P-2 to P-7 having the compositions as shown in Table 2 weresynthesized in the same manner as in Example 10 (synthesis of thepolymer P-1).

The properties of the obtained polymers P-2 to P-7 were measured, andthe results are shown in Table 2.

Comparative Example 12 Synthesis of the Polymers P-8 and P-9

The polymers P-8 and P-9 having the compositions as shown in Table 2were synthesized in the same manner as in Example 10 (synthesis of thepolymer P-1).

The properties of the obtained polymers P-8 and P-9 were measured, andthe results are shown in Table 2.

The names and the structural formulas of the raw material monomers usedin Example 11 and Comparative example 12 are as follows:

OTNMA: 2-exo-methacryloyloxy-4-oxatricyclo[4.2.1.0^(3,7)]nonan-5-one

OTNA: 2-exo-acryloyloxy-4-oxatricyclo[4.2.1.0^(3,7)]nonan-5-one

OTDMA: 8- or 9-methacryloyloxy-4-oxatricyclo[5.2.1.0^(2,6)]decan-3-one

OTDA: 8- or 9-acryloyloxy-4-oxatricyclo[5.2.1.0^(2,6)]decan-3-one

MAdMA: 2-methacryloyloxy-2-methyladamantane

MAdA: 2-acryloyloxy-2-methyladamantane

EAdMA: 2-methacryloyloxy-2-ethyladamantane

EAdA: 2-acryloyloxy-2-ethyladamantane

HAdMA: 1-methacryloyloxy-3-hydroxyadamantane

HAdA: 1-acryloyloxy-3-hydroxyadamantane

DMMB: 4,4-dimethyl-2-methylene-4-butanolide

M-1:5-methacryloyloxy-2-methyl-2-(1-adamantyl)-1,3-dioxolan-4-one

M-2:spiro[adamantane-2,2′-(4′-methacryloyloxypropyleneglycol-1,3′-dioxolane)

M-3: spiro[adamantane-2,2′-(4′-acryloyloxymethyl-1′,3′-dioxolane)

M4: spiro[norbornan-2,2′-(4′-acryloyloxymethyl-1′,3′-dioxolan-5-one)

M-5: 2-methyl-2-ethyl-4-methacryloyl-1,3-dioxolan-5-one

M-6: 4-acryloyloxymethyl-2-cyclohexyl-1,3-dioxolane

With regard to the polymers P-1 to P-9, the solubility in a resistsolvent, and the sensitivity, the dry etching resistance (etching rate)and the line edge roughness of the obtained resist patterns weremeasured and evaluated as follows. The results are shown in Table 2.

<Solubility in a Resist Solvent>

Each copolymer was dissolved in a certain amount of resist solvent(propylene glycol monomethyl ether acetate or ethyl lactate) at roomtemperature while stirring, so that the solid content became 20% bymass, and the time required for the copolymer to be completely dissolvedwas measured. The results are shown in Table 2.

Symbols in the table mean as follows:

⊚: The time required for the copolymer to be completely dissolved isless than 1 hour;

∘: The time required for the copolymer to be completely dissolved is 1hour or more, and less than 6 hours;

Δ: The time required for the copolymer to be completely dissolved is 6hours or more, and less than 24 hours;

x: The time required for the copolymer to be completely dissolved is 24hours or more, or the copolymer is insoluble.

<Formation of a Resist Pattern>

100 parts of each of the copolymers P-1 to P-9, and 2 parts oftriphenylsulfonium triflate were dissolved in a mixed solution of 630parts of propylene glycol monomethyl ether acetate and 70 parts ofγ-butyrolactone, so as to obtain a homogeneous solution. Thereafter, thesolution was filtered with a fluorocarbon resin filter, so as to preparea resist composition solution. And then, each of the preparedcomposition solutions was spin-coated on a 3-inch silicon wafer, andusing a hot plate, pre-bake was carried out at 120° C. for 60 seconds toform a thin film having a film thickness of 0.4 μm. Subsequently, thethin film was exposed using a light exposure system with a wavelength of193 nm (SP193 manufactured by Nikon Corporation), and then, using a hotplate, baking was carried out at 120° C. for 60 seconds. Thereafter,development was carried out at room temperature for 60 seconds using a2.38% by mass tetramethylammonium hydroxide aqueous solution, followedby washing with pure water and drying, so as to form a resist pattern.

The sensitivity, the dry etching resistance (etching rate) and the lineedge roughness of each of the obtained resist patterns were measured andevaluated as follows. The results are shown in Table 2.

<Sensitivity>

Sensitivity was defined as a light exposure (mJ/cm²), which forms aline-and-space pattern (line/space=1/1) at a line width of 1/1.

<Etching Rate>

The resist film formed on a silicon wafer was subjected to a dry etchingtreatment using a SPE-220T dry etching machine manufactured by ShowaShinku Co., Ltd. The dry etching treatment was carried out using CF₄/O₂mixed gas, for 2 minutes. The film thickness of the resist film wasmeasured before and after the dry etching treatment, using a Lambda AceVM-8000J light-interference type thickness measurement systemmanufactured by Dainippon Screen MFG Co., Ltd. Etching rate of theresist was defined as the reduced amount of the film thickness per unittime. Moreover, the etching rate was normalized by setting the etchingrate of a novolac resin as 1.

<Line Edge Roughness>

The minimum line width of the line of the formed line-and-space pattern(line/space=1/1) was subtracted from the maximum line width thereof, andthe obtained value was divided by the half-value width of the maximumline width of the line. The thus obtained value was defined as line edgeroughness.

TABLE 2 Comparative Examples 10 and 11 example 12 Polymer P-1 P-2 P-3P-4 P-5 P-6 P-7 P-8 P-9 Mass-average molecular weight (Mw) 11,000 12,50012,000 14,500 16,000 13,500 14,500 11,500 15,500 Molecular weightdistribution (Mw/Mn) 1.69 1.72 1.85 1.85 1.82 1.78 1.81 1.79 1.89Copolymerization OTNMA 45 40 50 composition ratio OTNA 35 40 (mol %)OTDMA 45 40 OTDA 40 45 MAdMA 45 50 MAdA 40 EAdMA 45 40 40 EAdA 40 40 40HAdMA 10 10 HAdA 10 15 5 20 M-1 10 M-2 10 M-3 10 M-4 10 10 M-5 10 M-6 10Sensitivity (mJ/cm²) 4.2 3.7 3.6 7.5 6.7 3.9 7.0 4.1 6.6 Etching rate1.02 1.01 1.04 1.04 1.03 1.06 1.07 0.99 1.01 Solubility PGMEA ◯ ◯ ⊚ ◯ ◯⊚ ◯ X X Ethyl lactate ⊚ ◯ ⊚ ⊚ ⊚ ⊚ ⊚ Δ Δ Line edge roughness 0.04 0.060.05 0.05 0.06 0.05 0.06 0.16 0.23

The polymers P-1 to P-7 of Examples 10 and 11, which were the polymersof the present invention, were more excellent in solubility in a resistsolvent than the polymers P-8 and P-9 of Comparative example 12.Moreover, the chemically amplified resist compositions of the presentinvention comprising the polymers P-1 to P-7 had sufficient sensitivityand etching resistance, and at the same time, the chemically amplifiedresist compositions had less line edge roughness than that of thechemically amplified resist compositions comprising the polymers P-8 andP-9.

INDUSTRIAL APPLICABILITY

The 5-methylene-1,3-dioxolan-4-one derivative of the present invention,which has, at position 2, a bridged cyclic hydrocarbon group or an alkylgroup having a bridged cyclic hydrocarbon group as a substituent, haspolymerization properties that are suitable for copolymerization withother monomers, and the obtained homopolymer and copolymer are excellentin light transparency and heat stability. Moreover, according to theproduction method of the present invention, the5-methylene-1,3-dioxolan-4-one derivative can be easily produced at ahigh yield and a high purity.

The polymer of the present invention is excellent both in solubility inan organic solvent (resist solvent) and in heat resistance, and thus, itis preferable as a resist composition resin. The resist composition ofthe present invention comprising this polymer has sufficientsensitivity, resolution and dry etching resistance, and also has littleline edge roughness. The resist composition of the present invention ispreferably used in deep ultraviolet excimer laser lithography andelectron beam lithography, and particularly in lithography using an ArFexcimer laser.

According to the pattern formation method of the present invention usingthe resist composition, a high-precision fine resist pattern can bestably formed.

1. A 5-methylene-1,3-dioxolan-4-one derivative represented by thefollowing formula (1):

wherein R¹ represents a bridged cyclic hydrocarbon group containing 4 to16 carbon atoms, or a linear or branched alkyl group containing 1 to 6carbon atoms which has a bridged cyclic hydrocarbon group containing 4to 16 carbon atoms as a substituent; R² represents a hydrogen atom, or alinear or branched alkyl group containing 1 to 6 carbon atoms; or R¹ andR² represent a bridged cyclic hydrocarbon group containing 4 to 16carbon atoms together with the carbon atom to which they are bound,provided that the alkyl group and the bridged cyclic hydrocarbon groupmay have at least one substituent selected from a group consisting of alinear or branched alkyl group containing 1 to 6 carbon atoms which maybe optionally substituted, a hydroxy group, a carboxy group, an acylgroup containing 2 to 6 carbon atoms, an alkoxy group containing 1 to 6carbon atoms, and a carboxy group esterified with an alcohol containing1 to 6 carbon atoms.
 2. A 5-halo-5-methyl-1,3-dioxolan-4-one derivativerepresented by the following formula (2):

wherein X represents a chlorine atom or a bromine atom; R¹ represents abridged cyclic hydrocarbon group containing 4 to 16 carbon atoms, or alinear or branched alkyl group containing 1 to 6 carbon atoms which hasa bridged cyclic hydrocarbon group containing 4 to 16 carbon atoms as asubstituent; R² represents a hydrogen atom, or a linear or branchedalkyl group containing 1 to 6 carbon atoms; or R¹ and R² represent abridged cyclic hydrocarbon group containing 4 to 16 carbon atomstogether with the carbon atom to which they are bound, provided that thealkyl group and the bridged cyclic hydrocarbon group may have at leastone substituent selected from a group consisting of a linear or branchedalkyl group containing 1 to 6 carbon atoms which may be optionallysubstituted, a hydroxy group, a carboxy group, an acyl group containing2 to 6 carbon atoms, an alkoxy group containing 1 to 6 carbon atoms, anda carboxy group esterified with an alcohol containing 1 to 6 carbonatoms.
 3. A method of producing a 5-halo-5-methyl-1,3-dioxolan-4-onederivative represented by the following formula (2):

wherein X represents a chlorine atom or a bromine atom; R¹ represents abridged cyclic hydrocarbon group containing 4 to 16 carbon atoms, or alinear or branched alkyl group containing 1 to 6 carbon atoms which hasa bridged cyclic hydrocarbon group containing 4 to 16 carbon atoms as asubstituent; R² represents a hydrogen atom, or a linear or branchedalkyl group containing 1 to 6 carbon atoms; or R¹ and R² represent abridged cyclic hydrocarbon group containing 4 to 16 carbon atomstogether with the carbon atom to which they are bound, provided that thealkyl group and the bridged cyclic hydrocarbon group may have at leastone substituent selected from a group consisting of a linear or branchedalkyl group containing 1 to 6 carbon atoms which may be optionallysubstituted, a hydroxy group, a carboxy group, an acyl group containing2 to 6 carbon atoms, an alkoxy group containing 1 to 6 carbon atoms, anda carboxy group esterified with an alcohol containing 1 to 6 carbonatoms, which comprises the step of: reacting a5-methyl-1,3-dioxolan-4-one derivative represented by the followingformula (3) with a halogenating agent at a reaction temperature within arange of 50° C. to 65° C.:

wherein R¹ represents a bridged cyclic hydrocarbon group containing 4 to16 carbon atoms, or a linear or branched alkyl group containing 1 to 6carbon atoms which has a bridged cyclic hydrocarbon group containing 4to 16 carbon atoms as a substituent; R² represents a hydrogen atom, or alinear or branched alkyl group containing 1 to 6 carbon atoms; or R¹ andR² represent a bridged cyclic hydrocarbon group containing 4 to 16carbon atoms together with the carbon atom to which they are bound,provided that the alkyl group and the bridged cyclic hydrocarbon groupmay have at least one substituent selected from a group consisting of alinear or branched alkyl group containing 1 to 6 carbon atoms which maybe optionally substituted, a hydroxy group, a carboxy group, an acylgroup containing 2 to 6 carbon atoms, an alkoxy group containing 1 to 6carbon atoms, and a carboxy group esterified with an alcohol containing1 to 6 carbon atoms.
 4. A method of producing a5-methylene-1,3-dioxolan-4-one derivative represented by the followingformula (1):

wherein R¹ represents a bridged cyclic hydrocarbon group containing 4 to16 carbon atoms, or a linear or branched alkyl group containing 1 to 6carbon atoms which has a bridged cyclic hydrocarbon group containing 4to 16 carbon atoms as a substituent; R² represents a hydrogen atom, or alinear or branched alkyl group containing 1 to 6 carbon atoms; or R¹ andR² represent a bridged cyclic hydrocarbon group containing 4 to 16carbon atoms together with the carbon atom to which they are bound,provided that the alkyl group and the bridged cyclic hydrocarbon groupmay have at least one substituent selected from a group consisting of alinear or branched alkyl group containing 1 to 6 carbon atoms which maybe optionally substituted, a hydroxy group, a carboxy group, an acylgroup containing 2 to 6 carbon atoms, an alkoxy group containing 1 to 6carbon atoms, and a carboxy group esterified with an alcohol containing1 to 6 carbon atoms, which comprises the step of: reacting the5-halo-5-methyl-1,3-dioxolan-4-one derivative represented by the belowformula (2) with an amide compound represented by the following formula(5) to carry out a dehydrohalogenation reaction:

wherein X represents a chlorine atom or a bromine atom; R¹ represents abridged cyclic hydrocarbon group containing 4 to 16 carbon atoms, or alinear or branched alkyl group containing 1 to 6 carbon atoms which hasa bridged cyclic hydrocarbon group containing 4 to 16 carbon atoms as asubstituent; R² represents a hydrogen atom, or a linear or branchedalkyl group containing 1 to 6 carbon atoms; or R¹ and R² represent abridged cyclic hydrocarbon group containing 4 to 16 carbon atomstogether with the carbon atom to which they are bound, provided that thealkyl group and the bridged cyclic hydrocarbon group may have at leastone substituent selected from a group consisting of a linear or branchedalkyl group containing 1 to 6 carbon atoms which may be optionallysubstituted, a hydroxy group, a carboxy group, an acyl group containing2 to 6 carbon atoms, an alkoxy group containing 1 to 6 carbon atoms, anda carboxy group esterified with an alcohol containing 1 to 6 carbonatoms,

wherein each of R³, R⁴ and R⁵ independently represents a hydrogen atom,or a linear or branched alkyl group containing 1 to 4 carbon atoms.
 5. Amethod of producing a 5-methylene-1,3-dioxolan-4-one derivativerepresented by the following formula (1):

wherein R¹ represents a bridged cyclic hydrocarbon group containing 4 to16 carbon atoms, or a linear or branched alkyl group containing 1 to 6carbon atoms which has a bridged cyclic hydrocarbon group containing 4to 16 carbon atoms as a substituent; R² represents a hydrogen atom, or alinear or branched alkyl group containing 1 to 6 carbon atoms; or R¹ andR² represent a bridged cyclic hydrocarbon group containing 4 to 16carbon atoms together with the carbon atom to which they are bound,provided that the alkyl group and the bridged cyclic hydrocarbon groupmay have at least one substituent selected from a group consisting of alinear or branched alkyl group containing 1 to 6 carbon atoms which maybe optionally substituted, a hydroxy group, a carboxy group, an acylgroup containing 2 to 6 carbon atoms, an alkoxy group containing 1 to 6carbon atoms, and a carboxy group esterified with an alcohol containing1 to 6 carbon atoms, which comprises the step of: reacting a5-halomethyl-1,3-dioxolan-4-one derivative represented by the followingformula (4) with an amide compound represented by the following formula(5) to carry out a dehydrohalogenation reaction:

wherein X represents a chlorine atom or a bromine atom; R¹ represents abridged cyclic hydrocarbon group containing 4 to 16 carbon atoms, or alinear or branched alkyl group containing 1 to 6 carbon atoms which hasa bridged cyclic hydrocarbon group containing 4 to 16 carbon atoms as asubstituent; R² represents a hydrogen atom, or a linear or branchedalkyl group containing 1 to 6 carbon atoms; or R¹ and R² represent abridged cyclic hydrocarbon group containing 4 to 16 carbon atomstogether with the carbon atom to which they are bound, provided that thealkyl group and the bridged cyclic hydrocarbon group may have at leastone substituent selected from a group consisting of a linear or branchedalkyl group containing 1 to 6 carbon atoms which may be optionallysubstituted, a hydroxy group, a carboxy group, an acyl group containing2 to 6 carbon atoms, an alkoxy group containing 1 to 6 carbon atoms, anda carboxy group esterified with an alcohol containing 1 to 6 carbonatoms; and

wherein each of R³, R⁴ and R⁵ independently represents a hydrogen atom,or a linear or branched alkyl group containing 1 to 4 carbon atoms.
 6. Apolymer obtained by (co)polymerizing a monomer composition comprising amonomer represented by the following formula (1):

wherein R¹ represents a bridged cyclic hydrocarbon group containing 4 to16 carbon atoms, or a linear or branched alkyl group containing 1 to 6carbon atoms which has a bridged cyclic hydrocarbon group containing 4to 16 carbon atoms as a substituent; R² represents a hydrogen atom, or alinear or branched alkyl group containing 1 to 6 carbon atoms; or R¹ andR² represent a bridged cyclic hydrocarbon group containing 4 to 16carbon atoms together with the carbon atom to which they are bound,provided that the alkyl group and the bridged cyclic hydrocarbon groupmay have at least one substituent selected from a group consisting of alinear or branched alkyl group containing 1 to 6 carbon atoms which maybe optionally substituted, a hydroxy group, a carboxy group, an acylgroup containing 2 to 6 carbon atoms, an alkoxy group containing 1 to 6carbon atoms, and a carboxy group esterified with an alcohol containing1 to 6 carbon atoms.
 7. A polymer comprising at least one ofconstitutional units represented by the following formula (6):

wherein R¹ represents a bridged cyclic hydrocarbon group containing 4 to16 carbon atoms, or a linear or branched alkyl group containing 1 to 6carbon atoms which has a bridged cyclic hydrocarbon group containing 4to 16 carbon atoms as a substituent; R² represents a hydrogen atom, or alinear or branched alkyl group containing 1 to 6 carbon atoms; or R¹ andR² represent a bridged cyclic hydrocarbon group containing 4 to 16carbon atoms together with the carbon atom to which they are bound,provided that the alkyl group and the bridged cyclic hydrocarbon groupmay have at least one substituent selected from a group consisting of alinear or branched alkyl group containing 1 to 6 carbon atoms which maybe optionally substituted, a hydroxy group, a carboxy group, an acylgroup containing 2 to 6 carbon atoms, an alkoxy group containing 1 to 6carbon atoms, and a carboxy group esterified with an alcohol containing1 to 6 carbon atoms.
 8. A polymer comprising at least one ofconstitutional units represented by the following formula (7) and atleast one of constitutional units represented by the following formula(81), (91) or (10):

wherein each of R⁶ and R⁷ independently represents a hydrogen atom, alinear or branched alkyl group containing 1 to 6 carbon atoms, a cyclichydrocarbon group containing 4 to 16 carbon atoms, or a linear orbranched alkyl group containing 1 to 6 carbon atoms which has a cyclichydrocarbon group containing 4 to 16 carbon atoms as a substituent; orR⁶ and R⁷ represent a cyclic hydrocarbon group containing 4 to 16 carbonatoms together with the carbon atom to which they are bound, providedthat the alkyl group and the cyclic hydrocarbon group may have at leastone substituent selected from a group consisting of a linear or branchedalkyl group containing 1 to 6 carbon atoms which may be optionallysubstituted, a hydroxy group, a carboxy group, an acyl group containing2 to 6 carbon atoms, an alkoxy group containing 1 to 6 carbon atoms, anda carboxy group esterified with an alcohol containing 1 to 6 carbonatoms;

wherein R⁸ represents a hydrogen atom or a methyl group, and R⁹represents a branched alkyl group containing 3 to 6 carbon atoms, acyclic hydrocarbon group containing 4 to 8 carbon atoms, or a bridgedcyclic hydrocarbon group containing 4 to 16 carbon atoms, provided thatthe alkyl group, the cyclic hydrocarbon group and the bridged cyclichydrocarbon group may have at least one substituent selected from agroup consisting of a linear or branched alkyl group containing 1 to 6carbon atoms which may be optionally substituted, a hydroxy group, acarboxy group, and a carboxy group esterified with an alcohol containing1 to 6 carbon atoms;

wherein R¹⁰ represents a hydrogen atom or a methyl group, and R¹¹represents a hydrogen atom, a hydrophilic functional group, a linear orbranched alkyl group containing 1 to 6 carbon atoms which has ahydrophilic functional group, a cyclic hydrocarbon group containing 4 to8 carbon atoms which has a hydrophilic functional group, or a bridgedcyclic hydrocarbon group containing 4 to 16 carbon atoms which has ahydrophilic functional group, wherein said hydrophilic functional groupis selected from the group consisting of hydroxyl, carboxy, amino,ketone, acid anhydride, ester, ether, lactone, imino and amide groups;provided that the alkyl group, the cyclic hydrocarbon group, the bridgedcyclic hydrocarbon group and the hydrophilic functional group may haveat least one substituent selected from a group consisting of a linear orbranched alkyl group containing 1 to 6 carbon atoms which may beoptionally substituted, a hydroxy group, a carboxy group, and a carboxygroup esterified with an alcohol containing 1 to 6 carbon atoms; and

wherein each of R¹² and R¹³ independently represents a hydrogen atom, amethyl group or an ethyl group, and q represents an integer of 1 to 4.9. The polymer according to claim 8, comprising reacted units of themonomer unit (91) having a hydroxyl hydrophilic functional group. 10.The polymer according to claim 8, comprising reacted units of themonomer unit (91) having a carboxy hydrophilic functional group.
 11. Thepolymer according to claim 8, comprising reacted units of the monomerunit (91) having an amino hydrophilic functional group.
 12. The polymeraccording to claim 8, comprising reacted units of the monomer unit (91)having a ketone hydrophilic functional group.
 13. The polymer accordingto claim 8, comprising reacted units of the monomer unit (91) having anacid anhydride functional group.
 14. The polymer according to claim 8,comprising reacted units of the monomer unit (91) having a lactonehydrophilic functional group.
 15. The polymer according to claim 8,comprising reacted units of the monomer unit (91) having an iminohydrophilic functional group.
 16. The polymer according to claim 8,comprising reacted units of the monomer unit (91) having an imidehydrophilic functional group.
 17. The polymer according to claim 8,comprising reacted units of the monomer unit (91) having an esterhydrophilic functional group.
 18. A polymer comprising at least oneconstitutional units represented by the following formula (6) and atleast one constitutional units represented by the following formula (8),(9) or (10):

wherein R¹ represents a bridged cyclic hydrocarbon group containing 4 to16 carbon atoms, or a linear or branched alkyl group containing 1 to 6carbon atoms which has a bridged cyclic hydrocarbon group containing 4to 16 carbon atoms as a substituent; R² represents a hydrogen atom, or alinear or branched alkyl group containing 1 to 6 carbon atoms; or R¹ andR² represent a bridged cyclic hydrocarbon group containing 4 to 16carbon atoms together with the carbon atom to which they are bound,provided that the alkyl group and the bridged cyclic hydrocarbon groupmay have at least one substituent selected from a group consisting of alinear or branched alkyl group containing 1 to 6 carbon atoms which maybe optionally substituted, a hydroxy group, a carboxy group, an acylgroup containing 2 to 6 carbon atoms, an alkoxy group containing 1 to 6carbon atoms, and a carboxy group esterified with an alcohol containing1 to 6 carbon atoms;

wherein R⁸ represents a hydrogen atom or a methyl group, and R⁹represents a linear or branched alkyl group containing 1 to 6 carbonatoms, a cyclic hydrocarbon group containing 4 to 8 carbon atoms, or abridged cyclic hydrocarbon group containing 4 to 16 carbon atoms,provided that the alkyl group, the cyclic hydrocarbon group and thebridged cyclic hydrocarbon group may have at least one substituentselected from a group consisting of a linear or branched alkyl groupcontaining 1 to 6 carbon atoms which may be optionally substituted, ahydroxy group, a carboxy group, and a carboxy group esterified with analcohol containing 1 to 6 carbon atoms;

wherein R¹⁰ represents a hydrogen atom or a methyl group, and R¹¹represents a hydrogen atom, a hydrophilic functional group, a linear orbranched alkyl group containing 1 to 6 carbon atoms which has ahydrophilic functional group, a cyclic hydrocarbon group containing 4 to8 carbon atoms which has a hydrophilic functional group, or a bridgedcyclic hydrocarbon group containing 4 to 16 carbon atoms which has ahydrophilic functional group, provided that the alkyl group, the cyclichydrocarbon group, the bridged cyclic hydrocarbon group and thehydrophilic functional group may have at least one substituent selectedfrom a group consisting of a linear or branched alkyl group containing 1to 6 carbon atoms which may be optionally substituted, a hydroxy group,a carboxy group, and a carboxy group esterified with an alcoholcontaining 1 to 6 carbon atoms; and

wherein each of R¹² and R¹³ independently represents a hydrogen atom, amethyl group or an ethyl group, and q represents an integer of 1 to 4.19. A polymer comprising at least one of constitutional unitsrepresented by the following formula (11):

wherein W¹ represents a direct bond or a methylene chain containing 1 to6 carbon atoms [—(CH₂)_(k)— (wherein k represents an integer of 0 to6)], W² represents a direct bond or a methylene chain containing 1 to 3carbon atoms [—(CH₂)₁— (wherein 1 represents an integer of 0 to 3)], W³represents a methylene chain containing 1 to 3 carbon atoms [—(CH₂)_(m)—(wherein m represents an integer of 1 to 3)], R¹⁴ represents a hydrogenatom or a methyl group, R¹⁵ represents a bridged cyclic hydrocarbongroup containing 4 to 16 carbon atoms, or a linear or branched alkylgroup containing 1 to 6 carbon atoms which has a bridged cyclichydrocarbon group containing 4 to 16 carbon atoms as a substituent, R¹⁶represents a hydrogen atom, or a linear or branched alkyl groupcontaining 1 to 6 carbon atoms; or R¹⁵ and R¹⁶ represent a bridgedcyclic hydrocarbon group containing 4 to 16 carbon atoms together withthe carbon atom to which they are bound, provided that the methylenechain containing 1 to 6 carbon atoms may be optionally substituted by anoptionally substituted alkyl group containing 1 to 3 carbon atoms, andmay optionally have at least one ether bond therein, the methylene chaincontaining 1 to 3 carbon atoms may have a carbonyl group therein, andthe alkyl group and the bridged cyclic hydrocarbon group may have atleast one substituent selected from a group consisting of a linear orbranched alkyl group containing 1 to 6 carbon atoms which may beoptionally substituted, a hydroxy group, a carboxy group, an acyl groupcontaining 2 to 6 carbon atoms, an alkoxy group containing 1 to 6 carbonatoms, and a carboxy group esterified with an alcohol containing 1 to 6carbon atoms.
 20. A polymer comprising at least one of constitutionalunits represented by the following formula (12):

wherein W⁴ represents a direct bond or a methylene chain containing 1 to6 carbon atoms [—(CH₂)_(n)— (wherein n represents an integer of 0 to6)], R¹⁷ represents a hydrogen atom or a methyl group, each of R¹⁸ andR¹⁹ independently represents a hydrogen atom, a linear or branched alkylgroup containing 1 to 6 carbon atoms, a cyclic hydrocarbon groupcontaining 4 to 16 carbon atoms, or a linear or branched alkyl groupcontaining 1 to 6 carbon atoms which has a cyclic hydrocarbon groupcontaining 4 to 16 carbon atoms as a substituent; or R¹⁸ and R¹⁹represent a cyclic hydrocarbon group containing 4 to 16 carbon atomstogether with the carbon atom to which they are bound, provided that themethylene chain containing 1 to 6 carbon atoms may be optionallysubstituted by an optionally substituted alkyl group containing 1 to 3carbon atoms, and may optionally have at least one ether bond therein,and the alkyl group and the cyclic hydrocarbon group may have at leastone substituent selected from a group consisting of a linear or branchedalkyl group containing 1 to 6 carbon atoms which may be optionallysubstituted, a hydroxy group, a carboxy group, an acyl group containing2 to 6 carbon atoms, an alkoxy group containing 1 to 6 carbon atoms, anda carboxy group esterified with an alcohol containing 1 to 6 carbonatoms.
 21. A polymer comprising at least one of constitutional unitsrepresented by the following formula (13), and at least one ofconstitutional units selected from a constitutional unit derived from amonomer of 2-(meth)acryloyloxy-2-methyl-adamantane,2-(meth)acryloyloxy-2-ethyladamantane, or derivatives having an alkylgroup on the cyclic hydrocarbon group of these monomers or aconstitutional units represented by the following formula (10):

wherein W⁵ represents a direct bond or a methylene chain containing 1 to6 carbon atoms [—(CH₂)_(x)— (wherein x represents an integer of 0 to6)], W⁶ represents a direct bond or a methylene chain containing 1 to 3carbon atoms [—(CH₂)_(y)— (wherein y represents an integer of 0 to 3)],W⁷ represents a methylene chain containing 1 to 3 carbon atoms[—(CH₂)_(n)— (wherein z represents an integer of 1 to 3)], R²⁰represents a hydrogen atom or a methyl group, each of R²¹ and R²²independently represents a hydrogen atom, a linear or branched alkylgroup containing 1 to 6 carbon atoms, a cyclic hydrocarbon groupcontaining 4 to 16 carbon atoms, or a linear or branched alkyl groupcontaining 1 to 6 carbon atoms which has a cyclic hydrocarbon groupcontaining 4 to 16 carbon atoms as a substituent; or R²¹ and R²²represent a cyclic hydrocarbon group containing 4 to 16 carbon atomstogether with the carbon atom to which they are bound, provided that themethylene chain containing 1 to 6 carbon atoms may be optionallysubstituted by an optionally substituted alkyl group containing 1 to 3carbon atoms, and may optionally have at least one ether bond therein,the methylene chain containing 1 to 3 carbon atoms may have a carbonylgroup therein, and the alkyl group and the cyclic hydrocarbon group mayhave at least one substituent selected from a group consisting of alinear or branched alkyl group containing 1 to 6 carbon atoms which maybe optionally substituted, a hydroxy group, a carboxy group, an acylgroup containing 2 to 6 carbon atoms, an alkoxy group containing 1 to 6carbon atoms, and a carboxy group esterified with an alcohol containing1 to 6 carbon atoms; and

wherein each R¹² and R¹³ independently represents a hydrogen atom, amethyl group or an ethyl group, and q represents an integer of 1 to 4.22. A polymer comprising at least one constitutional units representedby the following formula (11) or (12) and at least one of constitutionalunits represented by the formula (8), (9) or (10):

wherein W¹ represents a direct bond or a methylene chain containing 1 to6 carbon atoms [—(CH₂)_(k)— (wherein k represents an integer of 0 to6)], W² represents a direct bond or a methylene chain containing 1 to 3carbon atoms [—(CH₂)₁— (wherein 1 represents an integer of 0 to 3)], W³represents a methylene chain containing 1 to 3 carbon atoms [—(CH₂)_(m)—(wherein m represents an integer of 1 to 3)], R¹⁴ represents a hydrogenatom or a methyl group, R¹⁵ represents a bridged cyclic hydrocarbongroup containing 4 to 16 carbon atoms, or a linear or branched alkylgroup containing 1 to 6 carbon atoms which has a bridged cyclichydrocarbon group containing 4 to 16 carbon atoms as a substituent, R¹⁶represents a hydrogen atom, or a linear or branched alkyl groupcontaining 1 to 6 carbon atoms; or R¹⁵ and R¹⁶ represent a bridgedcyclic hydrocarbon group containing 4 to 16 carbon atoms together withthe carbon atom to which they are bound, provided that the methylenechain containing 1 to 6 carbon atoms may be optionally substituted by anoptionally substituted alkyl group containing 1 to 3 carbon atoms, andmay optionally have at least one ether bond therein, the methylene chaincontaining 1 to 3 carbon atoms may have a carbonyl group therein, andthe alkyl group and the bridged cyclic hydrocarbon group may have atleast one substituent selected from a group consisting of a linear orbranched alkyl group containing 1 to 6 carbon atoms which may beoptionally substituted, a hydroxy group, a carboxy group, an acyl groupcontaining 2 to 6 carbon atoms, an alkoxy group containing 1 to 6 carbonatoms, and a carboxy group esterified with an alcohol containing 1 to 6carbon atoms;

wherein W⁴ represents a direct bond or a methylene chain containing 1 to6 carbon atoms [—(CH₂)_(n)— (wherein n represents an integer of 0 to6)], R¹⁷ represents a hydrogen atom or a methyl group, each of R¹⁸ andR¹⁹ independently represents a hydrogen atom, a linear or branched alkylgroup containing 1 to 6 carbon atoms, a cyclic hydrocarbon groupcontaining 4 to 16 carbon atoms, or a linear or branched alkyl groupcontaining 1 to 6 carbon atoms which has a cyclic hydrocarbon groupcontaining 4 to 16 carbon atoms as a substituent; or R¹⁸ and R¹⁹represent a cyclic hydrocarbon group containing 4 to 16 carbon atomstogether with the carbon atom to which they are bound, provided that themethylene chain containing 1 to 6 carbon atoms may be optionallysubstituted by an optionally substituted alkyl group containing 1 to 3carbon atoms, and may optionally have at least one ether bond therein,and the alkyl group and the cyclic hydrocarbon group may have at leastone substituent selected from a group consisting of a linear or branchedalkyl group containing 1 to 6 carbon atoms which may be optionallysubstituted, a hydroxy group, a carboxy group, an acyl group containing2 to 6 carbon atoms, an alkoxy group containing 1 to 6 carbon atoms, anda carboxy group esterified with an alcohol containing 1 to 6 carbonatoms;

wherein R⁸ represents a hydrogen atom or a methyl group, and R⁹represents a linear or branched alkyl group containing 1 to 6 carbonatoms, a cyclic hydrocarbon group containing 4 to 8 carbon atoms, or abridged cyclic hydrocarbon group containing 4 to 16 carbon atoms,provided that the alkyl group, the cyclic hydrocarbon group and thebridged cyclic hydrocarbon group may have at least one substituentselected from a group consisting of a linear or branched alkyl groupcontaining 1 to 6 carbon atoms which may be optionally substituted, ahydroxy group, a carboxy group, and a carboxy group esterified with analcohol containing 1 to 6 carbon atoms;

wherein R¹⁰ represents a hydrogen atom or a methyl group, and R¹¹represents a hydrogen atom, a hydrophilic functional group, a linear orbranched alkyl group containing 1 to 6 carbon atoms which has ahydrophilic functional group, a cyclic hydrocarbon group containing 4 to8 carbon atoms which has a hydrophilic functional group, or a bridgedcyclic hydrocarbon group containing 4 to 16 carbon atoms which has ahydrophilic functional group, provided that the alkyl group, the cyclichydrocarbon group, the bridged cyclic hydrocarbon group and thehydrophilic functional group may have at least one substituent selectedfrom a group consisting of a linear or branched alkyl group containing 1to 6 carbon atoms which may be optionally substituted, a hydroxy group,a carboxy group, and a carboxy group esterified with an alcoholcontaining 1 to 6 carbon atoms; and

wherein each of R¹² and R¹³ independently represents a hydrogen atom, amethyl group or an ethyl group, and q represents an integer of 1 to 4.23. The polymer according to any one of claims 6 to 22, wherein itsmass-average molecular weight is within a range of 1,000 to 100,000. 24.A polymer mixture comprising at least one polymer according to any oneof claims 6 to 22, and at least one polymer comprising at least one ofconstitutional units represented by formula (8), (9) or (10):

wherein R⁸ represents a hydrogen atom or a methyl group, and R⁹represents a linear or branched alkyl group containing 1 to 6 carbonatoms, a cyclic hydrocarbon group containing 4 to 8 carbon atoms, or abridged cyclic hydrocarbon group containing 4 to 16 carbon atoms,provided that the alkyl group, the cyclic hydrocarbon group and thebridged cyclic hydrocarbon group may have at least one substituentselected from a group consisting of a linear or branched alkyl groupcontaining 1 to 6 carbon atoms which may be optionally substituted, ahydroxy group, a carboxy group, and a carboxy group esterified with analcohol containing 1 to 6 carbon atoms;

wherein R¹⁰ represents a hydrogen atom or a methyl group, and R¹¹represents a hydrogen atom, a hydrophilic functional group, a linear orbranched alkyl group containing 1 to 6 carbon atoms which has ahydrophilic functional group, a cyclic hydrocarbon group containing 4 to8 carbon atoms which has a hydrophilic functional group, or a bridgedcyclic hydrocarbon group containing 4 to 16 carbon atoms which has ahydrophilic functional group, provided that the alkyl group, the cyclichydrocarbon group, the bridged cyclic hydrocarbon group and thehydrophilic functional group may have at least one substituent selectedfrom a group consisting of a linear or branched alkyl group containing 1to 6 carbon atoms which may be optionally substituted, a hydroxy group,a carboxy group, and a carboxy group esterified with an alcoholcontaining 1 to 6 carbon atoms; and

wherein each of R¹² and R¹³ independently represents a hydrogen atom, amethyl group or an ethyl group, and q represents an integer of 1 to 4.25. A resist composition, which comprises the polymer mixture accordingto claim
 24. 26. A method of forming a pattern, which comprises thesteps of: coating the resist composition according to claim 25 onto asubstrate to be processed; exposing the substrate to a light with awavelength of 250 nm or shorter or an electron beam; and development.27. The method of forming a pattern according to claim 26, wherein thelight used for exposure is an ArF excimer laser.
 28. A method of forminga pattern, which comprises the steps of: coating the resist compositionaccording to 25 onto a substrate to be processed; exposing the substrateto a light with a wavelength of 250 nm or shorter or an electron beam;and developing it with a developing solution after subjecting it to aheat treatment, if necessary.
 29. The method of forming a patternaccording to claim 28, wherein the light used for exposure is an ArFexcimer laser.
 30. A resist composition, which comprises the polymermixture according to claim 24 and a photoacid generator.
 31. A method offorming a pattern, which comprises the steps of: coating the resistcomposition according to claim 30 onto a substrate to be processed;exposing the substrate to a light with a wavelength of 250 nm or shorteror an electron beam; and development.
 32. The method of forming apattern according to claim 31, wherein the light used for exposure is anArF excimer laser.
 33. A method of forming a pattern, which comprisesthe steps of: coating the resist composition according to 30 onto asubstrate to be processed; exposing the substrate to a light with awavelength of 250 nm or shorter or an electron beam; and developing itwith a developing solution after subjecting it to a heat treatment, ifnecessary.
 34. The method of forming a pattern according to claim 33,wherein the light used for exposure is an ArF excimer laser.
 35. Aresist composition, which comprises at least one polymer according toany one of claims 6 to
 22. 36. A method of forming a pattern, whichcomprises the steps of: coating the resist composition according toclaim 35 onto a substrate to be processed; exposing the substrate to alight with a wavelength of 250 nm or shorter or an electron beam; anddevelopment.
 37. The method of forming a pattern according to claim 36,wherein the light used for exposure is an ArF excimer laser.
 38. Amethod of forming a pattern, which comprises the steps of: coating theresist composition according to 35 onto a substrate to be processed;exposing the substrate to a light with a wavelength of 250 nm or shorteror an electron beam; and developing it with a developing solution aftersubjecting it to a heat treatment, if necessary.
 39. The method offorming a pattern according to claim 38, wherein the light used forexposure is an ArF excimer laser.
 40. A resist composition, whichcomprises at least one polymer according to any one of claims 6 to 22and a photoacid generator.
 41. A method of forming a pattern, whichcomprises the steps of: coating the resist composition according toclaim 40, onto a substrate to be processed; exposing the substrate to alight with a wavelength of 250 nm or shorter or an electron beam; anddevelopment.
 42. The method of forming a pattern according to claim 41,wherein the light used for exposure is an ArF excimer laser.
 43. Amethod of forming a pattern, which comprises the steps of: coating theresist composition according to 40 onto a substrate to be processed;exposing the substrate to a light with a wavelength of 250 nm or shorteror an electron beam; and developing it with a developing solution aftersubjecting it to a heat treatment, if necessary.
 44. The method offorming a pattern according to claim 43, wherein the light used forexposure is an ArF excimer laser.